Jerzy Janowicz continued his remarkable run of form as he reached the semi-finals of the Paris Masters on Friday, with the Polish qualifier leading 3-6, 6-1, 4-1 against eighth-seeded Janko Tipsarevic when the Serbian retired.
Janowicz saved one match point in his third-round win against Britain's Andy Murray on Thursday and had broken Tipsarevic for the second time in the third set when the Serb called for a trainer.
Tipsarevic continued for a few moments more, and Janowicz was 40-0 up on his serve when Tipsarevic waved his racket to indicate he was stopping, drawing jeers from the crowd at the Bercy indoor arena.
There were huge cheers for the 21-year-old Janowicz.
"It's really not easy for me to realise actually what is going on in my life right now,'' Janowicz said.
"I did something magical. I just played really like I can put every single ball in, and I'm in semi-final ... my family was crying after yesterday's match and after today's match.''
Organisers said that Tipsarevic, who qualified on Thursday for the season-ending World Tour Finals in London next week, started feeling fatigued at the end of the first set.
The 69th-ranked Janowicz faces Gilles Simon, who is also unseeded, in the semi-finals. The Frenchman earlier beat fifth-seeded Tomas Berdych of the Czech Republic 6-4, 6-4.
"I will play against French guy, but mentally I'm a really tough guy,'' Janowicz said.
"I remember in my match against Andy Murray in Great Britain during Davis Cup three years ago, whole crowd was against me, over 5,000 people. I didn't really care.''
Janowicz, who was playing in Futures tournaments at the start of the year and is still struggling for sponsorship back home, has beaten four players ranked in the top 20 on his way to the last four - Philipp Kohlschreiber (19) Marin Cilic (15), Murray (3) and now Tipsarevic (9). Simon is ranked 20th.
"Maybe because of this win I will get some bigger sponsor,'' Janowicz said, adding that he has been on every Polish television channel since beating Murray.
"This year I didn't go to Australian Open because I just didn't have money.''
Janowicz picked up his form in the second set, breaking Tipsarevic twice. The 21-year-old did not face a single breakpoint, and held to love on his service game to level the match.
Tipsarevic double-faulted twice in losing the third game of the third set and Janowicz then held to love with an ace on his second serve to open up a 3-1 lead. He broke Tipsarevic again with a booming forehand winner for 4-1.
At the changeover, Tipsarevic appeared to complain of feeling dizzy and stuck out his tongue while a trainer checked his throat.
Simon, meanwhile, fought back from 4-1 down in the second set to reach the last four here for the first time.
The Frenchman broke Berdych in the fifth game of the first set, but the match looked certain to go to a third set when Berdych secured an early break in the second and raced to 4-1.
But Simon secured two successive breaks of serve as he pressured Berdych's backhand and clinched the match with an ace, after Berdych saved one match point with an excellent backhand volley at the net.
"I'm happy to play well here because it's a tournament I love,'' Simon said.
"I grew up not far from here and I always used to watch the tournament. I've always wanted to do well.''
Simon improved to 5-2 in career matches against Berdych.
Berdych, the 2005 Paris Masters champion, thinks Simon - who reached a career high ranking of sixth in January 2009 - is close to being back to his best level.
"He played well, no question about it,'' Berdych said. "I haven't seen him play that well for quite a long time.''