Kei Nishikori "very proud" of career-high world ranking

Kei Nishikori has expressed his pride at reaching number four in the men's singles world rankings.

The Japanese player reached the career-high position thanks to his title win at the Memphis Open a fortnight ago, as well as reaching the final of the recent Mexican Open.

Writing on Twitter, the 25-year-old said: "Just saw the new rankings. Very proud of another step. #4 this week."

Former US Open finalist Nishikori was previously fifth in the standings, but he has now replaced Great Britain's Andy Murray in the top four.