WASHINGTON, Feb. 16 (Xinhua) -- Reilly Opelka of the United States edged past top-seeded fellow American John Isner 6-7(8), 7-6(14), 7-6(4) in the semifinal of the New York Open on Saturday as the pair set up a new ATP tour record of 81 aces in a three-set match.

Opelka fought off six match points in a marathon second set and went on to win the stunning match.

"I didn't put too much stress on myself. It's not the end of the world if I lose. I thought John served unbelievably well, he's the greatest server of all time, so that's what I expected," said the 21-year-old Opelka.

Opelka hit 43 aces and Isner had 38 aces. They shattered the previous record set by Australian player Nick Kyrgios and American Ryan Harrison (71) in January in Brisbane, with 44 aces for Kyrgios and 27 for Harrison.

It was similar to their meeting in the Australian Open when Opelka beat the ninth-ranked Isner in a first-round match that went four tiebreakers.

"Both of us were serving ridiculously well, so it was always going to come down to that," said Isner. "Essentially, heads I win, tails I lose, and it landed on tails."

World No. 89 Opelka will play Canadian Brayden Schnur, who beat American Sam Querrey 7-6(7), 4-6, 6-3.