John Isner of the United States returns to Kyle Edmund...

John Isner of the United States returns to Kyle Edmund of the United Kingdom during the third round of the U.S. Open tennis tournament at Billie Jean King National Tennis Center on Friday, Sept. 2, 2016. Credit: Kathleen Malone-Van Dyke

Clinging to his lifeboat serve, which regularly reached 137 miles per hour, John Isner was able to take young Briton Kyle Edmund to a fourth-set tiebreaker in their third-round U.S. Open match Friday night. But no farther.

Edmund, a 21-year-old ranked 84th in the world who upset No. 13 Richard Gasquet of France in the first round, held off No. 20 Isner, 6-4, 3-6, 6-2, 7-6 (5), to set up a fourth-round match with defending champion Novak Djokovic.

Isner, who leaves the tournament with a huge lead in aces with 100, struck 27 in the match — 11 of those in the last set as he was dangling over the abyss. Serving at 5-6 in the fourth, Isner pounded three consecutive aces to necessitate the tiebreaker.

He hit two more in the tiebreaker to keep the score at 3-3. But, from there, Isner’s inability to lift a backhand half-volley over the net gave Edmund a minibreak. Isner then lifted a lob long, followed by an Edmund forehand that caught less than an inch of the baseline to give him a triple match point at 6-3.

Isner’s inside-out forehand saved the first of those, and his service winner saved a second. But Edmund ripped a forehand to the open court to end the two-hour, 43-minute duel.

“Playing John,” Edmund said, “your chances don’t come often, so you have to catch those when they come. With his serve, when you get a racket on the ball, just try to keep it in the court.”

Edmund spoke several times during the first week of how, “In my head, I am thinking, ‘You’re creating good pressure here. Just keep patient . . .’ In my head, I am thinking, ‘It will come. Just don’t panic.’ ” He didn’t.

Earlier, Ryan Harrison, a 24-year-old qualifier based in Austin, Texas, playing in the third round for the first time, was beaten by veteran Cypriot Marcos Baghdatis, 6-3, 7-6 (4), 1-6, 6-1. In the second set, Harrison led, 5-3, before stumbling to the tiebreak.

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