How to complete a checkmate in this game? I have seen the ending position of this game in between Nakamura and Harikrishna. I sense a checkmate is close, but can't figure out what white should do after Qxg7. Please tell me how to complete the checkmate.

http://www.chessgames.com/perl/chessgame?gid=1744377
After 33... Qxg7, 34. Qxg7 is just mate in one. The queen is protected by the knight on h5. Black cannot avoid short-term mate at all, because Qxh7# is also a threat. He can stave it off with some desperate checks by the queen, e.g. 33... Qa1+ 34. Kh2 Qh1+ 35. Kxh1 but it is mate next move.

[FEN ""]
[White "Pentala Harikrishna"]
[Black "Hikaru Nakamura"]

1. e4 c5 2. Nf3 d6 3. Bb5 Nd7 4. O-O a6 5. Bd3 Ngf6 6. c3 b5 7. Bc2 Bb7 8. Re1 e5 9. d4 Be7 10. Nbd2 O-O 11. Nf1 Re8 12. Ng3 Bf8 13. d5 g6 14. b3 Nb6 15. Rb1 c4 16. bxc4 Nc4 17. a4 Qc7 18. axb5 axb5 19. Rb5 Na3 20. Rb3 Nc2 21. Qc2 Nd7 22. Be3 Ba6 23. Ra3 Bb5 24. Rea1 Ra3 25. Ra3 Rb8 26. Ra7 Qc8 27. h3 Nb6 28. Qc1 Nc4 29. Bh6 Qc5 30. Nh5 Bg7 31. Bg7 Qa7 32. Qh6 f5 33. Ng5 Qxg7 34. Qxg7#