Sam Querrey of the US lost to Japanese star Kei Nishikori 4-6, 7-5, 4-6 at the Citi Open here.
It was the first match Wednesday for the fourth seeded Nishikori since his Wimbledon's fourth round loss July 1, reports Xinhua.
Nishikori ended his three-match losing streak to Querrey after the victory.