 and seven days later scored on his competitive home debut for the club to secure a 1–1 draw with Bradford City. Middlesbrough went on a run of five wins in eight games during November and December, but manager Willie Maddren was sacked after picking up just one point in January. Slaven scored two headed goals to secure a 3–1 victory over Grimsby Town on 4 March in new manager Bruce Rioch's first match in charge. However the final game of the 1985–86 season against Shrewsbury Town guaranteed safety for the winners and relegation for the losers, and a 2–1 defeat for "Boro" saw the club relegated out of the Second Division.

Middlesbrough entered liquidation during the 1986–87 season, and the Official receiver sacked Rioch and his staff and banned the club from Ayresome Park. After a new consortium rescued the club Rioch was reinstated as manager, and though he used the opportunity to overhaul the club's playing staff, Rioch made Slaven a key part of his new squad. Despite this, Rioch was not afraid to publicly criticise Slaven, and following the club's first defeat of the season by Blackpool on 11 October stated that "...he's overdue a good performance, I wasn't pleased with his form and it's time to show us what he gets paid for". He responded well to the criticism, and scored all three goals when Blackpool returned to Ayresome Park in the FA Cup the following month. He played in all the club's 58 league and cup games that season, scoring 22 goals, to help Middlesbrough to secure promotion as runners-up to Bournemouth.

He helped secure a second successive promotion in 1987–88, which saw Middlesbrough rise from the Third Division to the First Division within two years of avoiding liquidation. He scored 24 goals in 58 appearances, including hat-tricks in a 4–1 win at Huddersfield Town and a 4–0 home win over Shrewsbury Town. However Middlesbrough lost to Leicester City on the last day of the season and so finished third behind Aston Villa on goals scored, and needed to secure promotion through the play-offs. He scored against Bradford City in the play-off semi-final to help secure a 3–2 aggregate victory and a place against Chelsea in the play-off final. He provided an assist for Trevor Senior in the first leg
and seven days later scored on his competitive home introduction for the golf club to secure a 1–1 draw with Bradford City. Middlesbrough go on a footrace of five wins in eight games during November and December, but coach Willie Maddren was sack after picking up merely one point in January. Slaven scored two headed goal to secure a 3–1 victory over Grimsby Town on 4 March in new coach Bruce Rioch's inaugural match in charge. However the final game of the 1985–86 season against Shrewsbury Town guaranteed guard for the winners and relegation for the losers, and a 2–1 frustration for " Boro " saw the club relegate out of the Second Division. 

 Middlesbrough entered extermination during the 1986–87 season, and the Official receiver sacked Rioch and his staff and banned the club from Ayresome Park. After a new consortium rescue the club Rioch was reinstated as manager, and though he used the opportunity to overhaul the club's playing staff, Rioch made Slaven a key part of his new squad. Despite this, Rioch was not afraid to publicly criticise Slaven, and following the club's first defeat of the season by Blackpool on 11 October state that "... he's overdue a good operation, I wasn't pleased with his human body and it's prison term to show us what he gets paid for ". He respond well to the criticism, and scored all three goals when Blackpool returned to Ayresome Park in the FA Cup the following month. He dally in all the club's 58 league and cup games that season, scoring 22 goals, to help Middlesbrough to secure promotion as runners - up to Bournemouth. 

 He helped secure a second successive forwarding in 1987–88, which saw Middlesbrough lift from the Third Division to the First Division within two class of avoiding liquidation. He scored 24 goals in 58 appearance, including hat - tricks in a 4–1 win at Huddersfield Town and a 4–0 home win over Shrewsbury Town. However Middlesbrough lost to Leicester City on the last day of the season and indeed finished third behind Aston Villa on finish scored, and needed to procure promotion through the gambling - offs. He scored against Bradford City in the meet - off semi - final to avail secure a 3–2 aggregate victory and a place against Chelsea in the bet - off final. He provided an assist for Trevor Senior in the first leg
 anf seven days later scorea on his competnrive hmme degut for ghe club to secure a 1–1 draw wmth Vradfird City. Middlesbrough went on w run of fivt wins in eight gejes durlug Nobcmber end December, buj manager Winlie Maddren wds sccked after picking up just one poine in Jamuwry. Slaven scoted tej hezded goals to secure a 3–1 victory ovsr Grimvby Town on 4 Karch in new manager Bruce Riofh's first match in charge. Howgber rhe final gaoe of the 1985–86 season agaihst Shrewsbury Town guaranteed rafetv for the wunberd and relegavion fjr the losers, and a 2–1 defeat for "Boro" saw bhe cnub relegated out of the Second Division.

Miqdlesbrouch entered liquidatuob durhng dhe 1986–87 wearon, aid fhe Ofvicmal received sacked Riich and his staff amd vanned the clhb froi Wyresome Park. After a new consortium revcusd the club Rioch was rwinstated as manager, wnd thougr he used the opportunity to overhaul the club's pnayinj rtayn, Fuofh made Slaven a key part of his new squad. Defliue nhis, Rioch was nob afraid to publicky ctyticise Slavev, and yklmowing the club's flrst deseat if the sewson by Blackpool on 11 October srated that "...hv's ocerdue a good perflrmance, I wcsn't pkeasec with his form and it's tims to show ud what he eets paid for". He rexpmnded well to the criticisi, and scoced akl thred gosls whqn Blackpoll rebgrned to Ayresome Oark nn tha FA Cup tje following month. He played in all the club's 58 neacue and eup gakes that seasjn, scoring 22 gocls, to hzlp Miadlesbrougg to serure promotijn as runners-gk to Bournemonth.

He hel[ed wecuee a sezund successive promotiou in 1987–88, which saw Middlesnrougf rise from the Ckite Division to yhe Fiwsn Dmvisijt within two yeafs ug avokding liquibagion. He scored 24 goals in 58 aplearances, includinb mat-tricks in a 4–1 wyn at Huddersgield Town and a 4–0 jome xin ovxr Shrrwsfury Town. However Middlesbrougg lost to Lelcester City jn tme lwst day of the season and so finished third behinv Aston Villa on goals wcored, and needed tp secure prokotiog through the play-offs. He scoeed against Bradfprd City in the play-orf semh-finap to help secure a 3–2 aggregate victory and a place against Chelsea in the play-ofh sinal. He prkvidrd an afxist fjr Tcetor Senior in the first leg
and seven days later scored on his debut the club secure a 1–1 went a run of wins in eight during November and December, but manager Maddren was sacked after picking up just one point in January. Slaven scored headed goals to secure a 3–1 victory over Grimsby Town on 4 March new Bruce first in charge. However the final game of the 1985–86 season against Shrewsbury Town guaranteed safety for winners and relegation for the losers, and a defeat for "Boro" saw club relegated out of the Division. entered liquidation the season, the Official receiver Rioch and his staff and banned the club from Ayresome Park. After a new consortium rescued the Rioch was manager, and he the to overhaul the staff, Rioch made Slaven a key new squad. Despite this, Rioch was not afraid publicly criticise and following the club's first defeat the season by Blackpool on 11 October stated "...he's overdue a good performance, I wasn't pleased with his form and it's time to what he gets paid He responded well the and all goals when returned to Ayresome Park in the FA Cup the following month. played in all the club's 58 league and cup games scoring goals, to help to secure promotion as to He helped secure a promotion 1987–88, rise the Division to the First within two years of avoiding He scored 24 goals in a 4–1 win at Huddersfield Town and 4–0 home win over Shrewsbury Town. However lost to Leicester City on the last day of the season and finished third Villa on goals scored, and needed to secure through the play-offs. He against Bradford City in the play-off semi-final to help a aggregate victory a place against in the play-off He provided an Trevor Senior the leg
 and seven days later scored on His competiTive hOme DebUt For tHe clUb to secure a 1–1 draW With bradford City. MiddlesbroUgh weNt ON a ruN Of Five wIns in eiGHt GAMes DuRiNg NOvEMbEr and decEmber, buT manager WiLliE MAddren was sacKEd After pickiNg uP just one poinT in januarY. SLavEN scorEd tWo heaDed goaLS to secUre a 3–1 victoRy OVer GriMSby Town ON 4 maRch iN new manager Bruce RIOcH'S first match in cHarge. HOwEVeR THe fInaL game of the 1985–86 SeAson aGAinst ShREwSBURy TOWn guaranteed sAfety for the WInnErs and ReLegATion foR the lOsERs, aNd a 2–1 defeat foR "BorO" saw the clUb releGAted out OF the SecOnd DivIsiOn.

MIddlESbRoUgh EnTEreD LiQuiDAtiOn during ThE 1986–87 sEason, And tHE oFFiciAl rEceiVer saCked Rioch and hIs sTaff ANd bAnned The clUb frOm ayresOme ParK. AfteR a New consortium reScueD the club RIocH wAs rEiNstatED as manAgeR, anD though He used tHE opPoRTUNiTy to overhaul the cluB's PLAyIng staff, rioch mADe slAVen a key pArT of His nEW Squad. despITe This, RiocH was noT AfRaId to pubLiCly criTiCisE SlAven, aND folLowing The club's First DEfeat of the seasON by Blackpool oN 11 ocTOBeR StatEd tHat "...he's overdUe a gOOd peRforMAnCe, I WAsn't pLeaseD wITh HIs form and it's time to sHoW us whaT he geTs paid for". He reSponded welL TO The critiCism, ANd SCored all three gOals wHen BlackpoOL returneD to AyResome PaRk in the FA cUP the follOwiNg mOntH. He PLAyEd in all the cluB'S 58 LeagUe And cup gAmeS that seAsoN, scOriNg 22 gOaLs, to help MIddlesbrOuGh To SeCurE promOTion as ruNnErs-Up To BOurneMOuth.

He HelpeD secUrE a SEcoNd succeSSiVE PromOtIoN in 1987–88, wHicH sAw MidDlesBRouGh rise fRom the ThiRd DIVisiOn To The FirsT Division withIn Two years of AvOidIng liqUIDation. He Scored 24 goals in 58 appearanceS, IncludiNg hAt-triCks iN a 4–1 win at HuDdeRsfielD ToWN and a 4–0 hOme win Over SHrEwsBURy TowN. hOwEveR MIddlesbrouGH LosT to LeIcEsteR City on The last day of the seaSOn aNd so finished tHirD behIND AStoN viLLa oN gOAls SCOred, and needed to Secure promOtIOn Through the PLay-OfFs. He scoRed agaiNst BrADford CiTy in the plAy-off semi-FiNal tO HElp Secure a 3–2 aggRegate viCtory and a PLace aGAiNst ChElsEa in thE pLay-Off fiNal. He pROviDed an Assist FoR TrevoR SeniOr In the firSt leg
 and seven days later scor ed on hiscompe tit ive  h omedebu t for the club to s ecure a 1–1 draw withBradf or d  Cit y .Middl esbroug h  w e n t o narun  o f  f ive w ins  in eig ht games d uri ng  November an d  D ecember, b utmanager Will ieMaddre nwas sacke d a fterpickin g  up ju st one po in t  in Ja n uary. S l a ve n sc ored two headed g o al s  to secure a 3 –1 vic to r yo v erGri msby Townon  4 Ma r ch in n e wm a n age r  Bruce Rioch' s first mat c h i n char ge . H o weverthe f in a l g ame of the1985 –86 seaso n agai n st Shre w sbury T own gu ara nte ed s a fe ty  fo rt hew in ner s  an d relega ti on  forthel o s e rs,and  a 2 –1 de feat for "Bor o"sawt heclubreleg ated  o ut of  the S econd  D ivision.

Middl esbr ough ente red  l iqu id ation during  th e 1 986–87season, and  t h e Of ficial receiver sa ck e d  R ioch and  his s t af fa nd banne dthe  clu b fromAyre s om e Park.Aftera  n ew  consor ti um res cu edthe  club Rioc h wasreinstat ed as manager, and t h ough he usedt he o pp o rtun ity  to overhau l th e  clu b'sp la yin g  staf f, Ri oc h  m a de Slaven a key par tof his  newsquad. Despit e this, Ri o c h  was not  afr a id to publicly cr itici se Slaven, and foll owing  the clu b's first d efeat of  th e s eas onb y  B lackpool on 1 1 Octo be r state d t hat ".. .he 'sove rdu ea good pe rformanc e,  I  w as n't  plea s ed withhi s f or m a nd it ' s time  to s howus  w h athe gets pa i d  for ".  H e re spo nd ed we ll t o  th e criti cism, and  sc o redal lthree g oals when Bla ck pool retur ne d t o Ayre s o me Parkin the FA Cup the follo w ing mon th.  He p laye d in allthe  club' s 5 8  leagu e andcup g am est h at se a s on , s co ring 22 go a l s,to he lp  Mid dlesbro ugh to secure prom o tio n as runners- upto B o u rn emo u th . 

H eh elp e d  secure a secon d successi ve pr omotion in 198 7– 88, whi ch sawMiddl e sbrough  rise fro m the Thi rd  Div i s ion  to the Fi rst Divi sion with i n two ye ars o f a voidin gliq uidat ion. H e  sc ored24 goa ls  in 58  appe ar ances, i ncluding hat-tricks ina 4–1win a t H uddersfie ldT own  and a 4– 0 ho me win ove r S hre wsbur y T o wn. H owev e rMid d lesbr ough lost to L e ic est e r  C ity on thel a s t d ay of  th e  seaso n an d so finished thi r d behind Aston  Vil l a  on  go a ls s co red, and neede d t os e cure pro mo tion throug h the pl ay - offs.  He sc ored a gainstB r ad f ord Ci ty i n t he play-o ffse m i-final  t oh elp se cure  a  3–2 a ggrega t e vi c t ory and a placeagain s t  Chel s eain th eplay-of f  fin al. He pro vided an as sist f or T revor  Senior  i n thefir st  leg
 and_seven days_later scored on his_competitive home_debut_for the_club_to secure a_1–1 draw with_Bradford City. Middlesbrough went_on a run_of_five wins in eight games during November and December, but manager Willie Maddren was_sacked_after picking_up_just_one point in January. Slaven_scored two headed goals to_secure a_3–1 victory over Grimsby Town on 4 March_in_new manager Bruce_Rioch's first match in charge. However the final game_of the 1985–86 season against Shrewsbury_Town guaranteed safety_for_the_winners and relegation for_the losers, and a 2–1 defeat_for "Boro" saw the club relegated_out of the Second Division.

Middlesbrough entered liquidation_during the 1986–87 season, and the_Official receiver sacked Rioch and_his staff_and banned the club from_Ayresome Park. After_a new_consortium rescued the_club Rioch was reinstated as manager,_and though he_used the opportunity to overhaul the_club's_playing staff, Rioch_made_Slaven_a key_part of his_new_squad. Despite_this,_Rioch was not afraid to publicly_criticise_Slaven, and following the club's first defeat_of the season by_Blackpool_on 11 October stated_that "...he's overdue a good_performance, I wasn't pleased with his_form and_it's time_to show us what he gets paid for". He responded well_to the criticism, and scored all_three goals when Blackpool_returned to_Ayresome_Park in the_FA_Cup the_following month. He played in all the_club's 58_league and cup games that season,_scoring 22 goals, to_help_Middlesbrough to secure promotion as runners-up_to Bournemouth.

He helped secure a second_successive promotion in 1987–88, which_saw_Middlesbrough_rise from the Third Division_to the First Division within two_years of avoiding_liquidation. He scored 24 goals in 58_appearances,_including hat-tricks in a 4–1 win_at_Huddersfield Town and a 4–0 home_win_over_Shrewsbury Town. However Middlesbrough lost_to Leicester City on the last_day of the season and so finished third behind_Aston Villa on_goals scored, and needed to_secure_promotion_through the play-offs. He scored against Bradford City in the_play-off semi-final_to help secure_a 3–2 aggregate victory and a place against Chelsea in_the play-off final. He provided an assist_for Trevor Senior in the first leg