The 6-foot-9 American had won all six tiebreaks so far at the U.S. Open, including three against Gilles Simon in the round of 16. In a tiebreak and at the net might have been exactly where Isner had hoped to find himself in a spot like this, down two sets to one and fighting to reach a fifth against a higher seed.
"I felt comfortable," Isner said. "He just outplayed me."
Isner doublefaulted and, after coming to the net on two straight points, thumped them into the net to bring up match point. "That hurt," Isner said. The 28th seed then picked up his racket to examine it before heading to the baseline, where Murray reached the semifinal with an unreturnable serve, 7-5, 6-4, 3-6, 7-6 (2).
"Good stuff," Murray said to Isner as they walked to shake the chair umpire's hand.
It was quality match. Isner's serve didn't dominate the structure of every point, although it was tough for Murray to corral. Isner came to the net 75 times and won 67 of those points, while Murray stayed more to the baseline and won 53 percent of those. Isner broke Murray once in six chances, in the third set, while Murray won two of his five break points.
"You can't take chances against someone that's serving 140 miles an hour and their second serve is bouncing, you know, like up here on the second serve, and then he's mixing it up with 120 miles an hour second serves into your body," Murray said. "You've just got to try and find a way to win, and I did that."
During his news conference, Murray kept stealing glances at a television monitor showing a live feed of the match between Rafael Nadal and Andy Roddick. After a while he stopped trying to pretend and seemed to address all his answers to the screen where Nadal had a significant lead.
"Well, I've beat him before in the semis, I won against him also at the Australian Open," Murray said. "And when I've won against him, it's always been on hard courts. It's a good surface for me to play him on."
Isner said it took him two sets to get comfortable with the wind on the Arthur Ashe Stadium court, and the way the light angled down.
"I was a little bit nervous," Isner said. "I think that comes with the fact that, again, I wasn't swinging out like I felt like I should have early on in the match. I was just guiding the ball."
It was just the second time these two had played. Murray, an ATP Tour stalwart, beat Isner in three at the Australian Open this year, 7-6 (4), 6-3, 6-2 in the fourth round. Despite Murray's experience, at 24 he is actually two years younger than Isner.
Murray has reached the semifinal round of all three Grand Slam events so far this year. He's just the seventh man to accomplish that in the open era. The other names on that list? Rod Laver, Tony Roche, Ivan Lendl, Roger Federer, Rafael Nadal and Novak Djokovic. The current four on that list are all into the U.S. Open semis.
"I think it's good for tennis," Murray said. "I think everyone has played great tennis in the slams this year. That's, I think, probably what people would like to see, would be you to play your best tennis there."
Of those four, Murray is the only to have never won a major.
Isner turned pro in 2007 after playing for the University of Georgia, while Murray started on the tour in 2005. Isner will always be remembered for his part in the longest match ever played, taking 11 hours over the course of three days to beat Nicolas Mahut at Wimbledon in 2010.
But the result here at the U.S. Open is the best of Isner's career. He had never reached a Grand Slam quarterfinal, and he was one of four American men to reach the round of 16. A few said Isner was playing well enough to go further. Indeed, his first service game against Murray included a 140 mile-per-hour ace.
"It's been a good run for me but I'm still disappointed," Isner said. "I would've liked my chances in a fifth set."