Monfils downs Dimitrov in three
Gael Monfils upset Grigor Dimitrov in unexpectedly comprehensive fashion to reach his second US Open quarter-final.
It was the best match-up of the fourth round in the bottom half of the draw but seventh seed Dimitrov was off his game and went down 7-5 7-6 (8/6) 7-5.
Monfils, who is likely to meet Roger Federer next, is one of the most enigmatic characters on tour and infuriates as much as he entertains with his frequent inability to turn talent into results.
But for most of Tuesday's match, which was played in high humidity, he was calm and controlled, allowing Dimitrov to implode under the weight of expectation.
The Bulgarian cracked first in the 11th game of the opening set, with Monfils serving it out confidently.
The Frenchman saw an early break slip away in the second and had a brief meltdown but it was Dimitrov who collapsed in the tie-break, four errors from 6-4 handing the set to Monfils.
And when he served to stay in the match in the 12th game of the third, Dimitrov again faltered, finishing the contest with a meek double fault.
Monfils' only previous trip to the last eight at Flushing Meadows came four years ago, when he lost to Novak Djokovic.
The Frenchman, who is yet to drop a set, also made the quarter-finals at the French Open this year, going down in five sets to Andy Murray.
Monfils said: "I'm happy because I played good. I think I played solid. I hit the ball better day after day, I served better. I keep simple things in my head, so obviously it is working.
"Then it's luck. Look at set point. I hit one of the worst drop shots I ever hit and he hit a frame. It's pure luck to not drop a set. So you need to have it sometimes, and I hope I will have more."
The Frenchman, who turned 28 on Monday, has been without a coach for the past 18 months.
"It's better to have someone to help you," he said. "I need it, but it's not easy. That person has to be good, first of all, but has to be hard and also understand my personality. Because I don't think I'm easy, but I think I'm quite a good worker."
Dimitrov had been seeded to meet Federer in what would have been a first grand slam meeting between the 17-time grand slam champion and the man nicknamed 'Baby Fed'.
The Bulgarian offered no excuses, saying: "It was a very poor match for me. I didn't play close to the way I wanted to, and I think it was a great stage for me to come out on there on the centre court and perform my best.
"Just everything went the opposite way today. I don't have to be too down for that. Of course I have to give credit to Gael that he played a really good match, but I also did a lot of unforced errors and that cost me a lot."
Dimitrov, who made the quarter-finals at the Australian Open and semi-finals of Wimbledon, admitted the occasion got to him in certain moments.
He said: "What I can do better next time is maybe approach matches like that a little different, especially when you get into the second week.
"If you're in the second week, you have good momentum and you should use it in your favour. Today I occasionally was a bit anxious at some points and I was going for a few shots that were not supposed to be played that way."
Fourteenth seed Marin Cilic reached his second straight grand slam quarter-final with a gruelling 5-7 7-6 (7/3) 6-4 3-6 6-3 victory over Gilles Simon.
The Croatian, who missed last year's tourna ment following a positive doping test, had never beaten Simon in four previous attempts and celebrated exuberantly at the end.
Cilic said: "It's amazing and really important. I knew Gilles would not go away that easily. All of our matches were very close but eventually he was always winning.
"I was mentally focused to be always in the game even though I lost the fourth set. I think I played really well in that last set."
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