Two-time champion Kei Nishikori has signed on to defend his Japan Open crown in October, the Japan Tennis Association announced Thursday.
In addition to world No. 4 Nishikori, the tournament, which kicks off on Oct. 5 at Tokyo's Ariake Colosseum, will feature French Open champion Stan Wawrinka of Switzerland, ranked fifth in the world, and ninth-ranked Marin Cilic of Croatia, who defeated Nishikori in last year's U.S. Open final.