You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "who won us open men's single 2018?" whose answer is Novak Djokovic.
Each document should contain about 30 words, and these documents should contain useful information.

Query: us open men's singles 2018 winner
Useful Output:

Doc 1: Just a few hours after becoming the 2018 U.S. Open men's singles champion, Novak Djokovic was seen in New York City perfecting “a different
Doc 2: Novak Djokovic produced an impeccable performance to beat Juan Martin del Potro in the US Open final and win his 14th Grand Slam title.
Doc 3: Novak Djokovic defeats Juan Martin del Potro, wins mens U.S. Open final  2018 US Open at the USTA Billie Jean King National Tennis
Doc 4: Novak Djokovic defeats Juan Martin del Potro to win 2018 US Open, 14th career Grand Slam  Novak Djokovic, of Serbia,
Doc 5: Djokovic a two-time US Open champ and 13-time Grand Slam winner, was just that much better than Nishikori in a 6-3, 6-4, 6-2 win to reach his