By Larry Fine
NEW YORK (Reuters) - Briton Andy Murray beat big-serving John Isner 7-5 6-4 3-6 7-6 on Friday, holding off the tiebreaker specialist 7-2 in the fourth-set decider to reach the U.S. Open semi-finals.
The first three sets were decided by single breaks of serve, with the fourth going to a tiebreak as neither player could break through in a tight match played in hot, sunny conditions at Arthur Ashe Stadium.
Isner, winner of 13 of his last 14 tiebreakers in U.S. Open play, including three in his four-set victory on Thursday over 12th seed Gilles Simon of France, looked poised to take Murray to a fifth set.
But the 24-year-old Scotsman beat the 22nd-ranked Isner at his own game, sharpening his play as the towering 6-foot-9 American began to crumble.
Isner, playing in his first grand slam quarter-final, double-faulted on the third point of the decider to give Murray the early advantage and netted an easy forehand volley to fall behind 5-2. Two points later he hit a serve return wide to end the three-hour 24-minute match.
"It's so frustrating playing against him," Murray told a center court crowd that included U.S. First Lady Michelle Obama, who was sitting in a box with former tennis great Billie Jean King.
"You feel like you're playing good tennis, but it's so tough to break him. He started serving unbelievable."
Fourth-seeded Murray will play either defending champion Rafa Nadal or 2003 winner Andy Roddick in the semi-finals.
A three-time grand slam finalist, Murray is trying to become the first Briton to win a grand slam singles crown since Fred Perry won his third U.S. Open in 1936.
(Editing by Frank Pingue)