NEW YORK: Past US Open runners-up Kei Nishikori advanced to the third round of the Grand Slam event on a rainy Wednesday.
Japanese seventh seed Nishikori, the 2014 US Open runner-up and a semi-finalist in 2016 and 2018, defeated 108th-ranked American Bradley Klahn 6-2, 4-6, 6-3, 7-5 after two hours and 44 minutes.
Next in Nishikori´s path will be either Australian Alex de Minaur or Chilean 31st seed Cristian Garin.
Top-ranked defending champion Novak Djokovic, 20-time Grand Slam winner Roger Federer and six-time US Open champion Serena Williams are set for later matches at Arthur Ashe Stadium.
US eighth seed Williams, seeking a 24th career Grand Slam title to match the all-time record won by Margaret Court, faces 17-year-old US wildcard Caty McNally.
Williams, 37, had won her first Slam title at the 1999 US Open and reached her second Flushing Meadows final before 121st-ranked McNally was born.
Djokovic, winner of four of the past five Slam titles and 16 in all, meets Argentina´s 56th-ranked Juan Ignacio Londero in the other night feature. The Serbian star is trying to become the first back-to-back Open champion since Federer´s run from 2004-2008.
Swiss third seed Federer, who lost to Djokovic in last month´s epic five-set Wimbledon final, meets 99th-ranked Bosnian Damir Dzumhur. Federer, 38, hasn´t fallen in a Slam second round since 2013 at Wimbledon.
Nishikori, who could face Federer in the quarter-finals, broke twice and took the first set in 28 minutes.
Klahn battled back and broke in the 10th game to claim the second set, but Nishikori dominated from there to a 5-1 lead in the fourth set.
Klahn saved a match point in the seventh game to start a run where he won 12 of 15 points. He denied another Nishikori match point and held serve to 5-5.
But Nishikori held again and then seized three more match points on Klahn, the American finally succumbing on the last of them when he smacked a backhand beyond the baseline.