3rd-seeded Isner ousted in first match at Memphis updated 11:04 p.m. MEMPHIS, Tennessee (AP) -Denis Istomin took advantage a sluggish John Isner to eliminate the third-seeded American 6-4, 6-3 on Tuesday in the U.S. National Indoor Tennis Championships. Isner struggled through a number of unforced errors and at least a handful of double faults. Istomin of Uzbekistan, ranked 63rd in the world, broke Isner in the seventh game of the first set as Isner hit two shots into the net and sailed a backhand long in the game. After gaining another break in the fifth game of the second set, Istomin won the set at love on Isner's serve, game point coming on a cross-court passing shot with Isner at the net. The victory was Istomin's first win over a top-20 opponent since he defeated Fernando Verdasco of Spain, then ranked 18th, in the London Olympics last year. "I know it's going to be a difficult match for me, and I need to concentrate and take each chance I had," Istomin said. I did this. I did good. I broke him in the first set, and then I started to feel better on the returns, and I started to read where he served. Earlier in the day, fourth-seeded Sam Querrey of the United States defeated Alejandro Falla of Columbia 6-3, 6-3 to advance to the tournament's second round. In the late match, fifth-seeded Kei Nishikori of Japan ousted qualifier Illya Marchenko of Ukraine 6-4, 7-5. In the women's draw, third-seeded Sabine Lisicki of Germany defeated qualifier Madison Keys of the United States 7-5, 6-3 and seventh-seeded Magdalena Rybarikova of Slovakia beat American Lauren Davis 7-6 (2), 6-2.