Grigor Dimitrov has knocked favourite Roger Federer out of the US Open, beating the Swiss ace for the first time to reach the semi-finals on Wednesday (NZT).
Federer gave away a lead against the Bulgarian and was beaten 3-6 6-4 3-6 6-4 6-2 by the 78th-ranked Bulgarian before a stunned crowd at Arthur Ashe Stadium.
The 38-year-old Federer took a rare medical timeout after the fourth set, leaving the court with a trainer.
It was not immediately clear what might have been wrong with Federer, although he did appear to be flexing his back after some points.
When play resumed after a break of nearly 10 minutes, Federer's form never picked up. He finished with 61 unforced errors, 33 on the forehand side.
Federer had been 7-0 against Dimitrov, taking 16 of their previous 18 sets.
Federer would have been the oldest Grand Slam semi-finalist since Jimmy Connors was 39 at Flushing Meadows in 1991.
He also was trying to add to his totals of five US Open championships and 20 major trophies in all.
Instead, Dimitrov advanced to his third major semi-final, first in New York. He will face No. 5 Daniil Medvedev on Saturday.
Earlier, Daniil Medvedev remained on course for a US Open title by taming Stan Wawrinka to reach his first grand slam semi-final.
The fifth-seeded Russian saved a set point in the opening tiebreaker and twice needed extensive treatment on his legs as he ended the run of the Swiss veteran 7-6 (8-6) 6-3 3-6 6-1 in two hours and 34 minutes.
Wawrinka, the 2016 champion, might have felt he might have another retirement on his hands, having seen previous opponent Novak Djokovic throw in the towel two nights earlier, but that was not the case on Wednesday.
Medvedev improved his tour-leading total to 49 victories this year to become the youngest semi-finalist in New York since Novak Djokovic in 2010.
"It was a really strange match. I had real pain in my quadriceps and thought I couldn't finish. I feel really strange but I am happy to be in my first major semi," Medvedev said.
Medvedev was public enemy No.1 among the Flushing Meadows fans after he flipped them a 'visual obscenity' during his third-round match last week and provoked
them again by performing a dance after claiming victory in the fourth round.
But there were none of those antics or sparring with the crowd on Tuesday as a focused Medvedev put his head down and got on with the job before extending an olive branch to the crowd.
"I have to say sorry guys and thank you," a sheepish Medvedev said in his on-court interview.
"I have two words (to describe the US Open).
"First one for sure 'electric' because it is electric and second 'controversy' because what I have done is not good.
"So many people support me still, so many people like my interview, so many people don't like me and I can just say I try to be myself guys."
Having reached three consecutive ATP Tour finals coming into Flushing Meadows, including a maiden Masters 1000 title win in Cincinnati, Medvedev looked much more like the hottest player in tennis in a dominant second set.
Yet the barrel-chested Swiss broke Medvedev at the first opportunity in the third before holding on to force a fourth set.
Medvedev, however, grabbed the early break in the fourth and a second to go 5-1 up before closing out the match with a cheeky lob.
Reuters