NEW YORK - Eccentric Frenchman Gael Monfils reached his second US Open quarter-final on Tuesday, stunning seventh-seeded Grigor Dimitrov 7-5 7-6 (8-6) 7-5.
Crowd favourite Monfils overcame a dramatic loss of composure in the second set to book a last-eight date with either five-time champion Roger Federer or Spain's Roberto Bautista Agut.
"It's my first ever win on the Ashe stadium which is great," said the 20th seed who also reached the quarter-finals in 2010.
"I love to play in New York. There is so much energy and it helps me deliver my game."
Monfils also said playing without a coach seemed to be working for him.
"I guess I should stay this way," added the French star who will be looking to equal his best grand slam performance of a 2008 run to the French Open semi-finals.
Wimbledon semi-finalist Dimitrov was hoping to reach his third quarter-final at the majors this year but despite occasional breath-taking shot-making, he was undone by 38 unforced errors.
Monfils had celebrated his 28th birthday on Monday and the feel good factor took him racing through the first set on the back of a break for a 6-5 lead.
The Frenchman was another break to the good at 4-2 in the second before he got embroiled in a brief war of words seemingly directed at Dimitrov's player box.
Still seething, the Parisian then surrendered a break point by not returning the ball in the eighth game.
But he bounced back in impressive style, saving two set points in the tiebreak before winning four points in a row to open a two sets to love lead.
Wimbledon semi-finalist Dimitrov, who had never won a match in New York on his three previous visits, was facing having to come back from two sets to love down for the first time in his career.
But his luck didn't change and his campaign was over when he served up his fourth double fault of the tie.
Meanwhile Croatian 14th seed Marin Cilic reached his third US Open quarter-final with a 5-7 7-6 (7-3) 6-4 3-6 6-3 win over France's Gilles Simon.
Cilic, also a quarter-finalist in 2009 and 2012, will face either Tomas Berdych of the Czech Republic or Austria's Dominic Thiem for a place in the semi-finals.
Cilic hit 23 aces, 70 winners and committed 76 unforced errors in the four hour 13 minute clash.
His victory comes 12 months after he was forced to miss the tournament as he sat out a doping ban.