NEW YORK (AP) — Andy Murray shrugged off a poor first-set tiebreaker to beat Denis Istomin 6-7 (5), 6-1, 6-4, 6-4 on Tuesday to advance to the quarterfinals of the U.S. Open for the third-straight year.

The defending champion came apart after leading 5-3 in the opening-set tiebreaker.

First, Istomin hit a forehand winner to close a 27-shot exchange. Then Murray, distracted before his service toss by a shout from the stands, double-faulted. A forehand into the net gave Istomin a set point and the Uzbek took the set when Murray pushed a backhand wide.

Istomin was broken right away in the second set and, aside from winning a point with a no-look between-the-legs shot in the last game, there were few highlights as the match was squared at one set all.

There was more shakiness from Murray in the third set, in which he went up a break, only to lose serve to make it 3-3. But he broke right back for a 4-3 edge, and was back on his way to a victory that improved his record over his past five Grand Slam tournaments to 30-2.

His opponent in the last eight will be Stanislas Wawrinka, who reached his second U.S. Open quarterfinal by eliminating Tomas Berdych 3-6, 6-1, 7-6 (6), 6-2.

Murray leads the head-to-head series against Wawrinka 8-5, but they've split their two previous meetings on the U.S. Open's hard courts: Murray won in 2008, and Wawrinka won two years later. Wawrinka also won their only match this season, 6-1, 6-2 on red clay at Monte Carlo in April.

"He's very tough. Very talented," Murray said. "We played once on this court when we were much younger. But a lot has changed since then."

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