Former world No. 4 Kei Nishikori advanced to the quarterfinals of the Japan Open tennis tournament Saturday with a 6-2, 6-3 victory over Australia’s Jordan Thompson. Nishikori, currently ranked 200th, converted five of his seven break points while allowing Thompson to break his serve only once at Ariake Colosseum. The match ended when Thompson, who has risen to a career-high rank of 29th, double-faulted when trailing 15-40. Nishikori will next play the winner of the second-round match between Japanese compatriot Yoshihito Nishioka and Denmark’s Holger Rune. Thompson was facing Nishikori after …