PARIS (AP) - Polish qualifier Jerzy Janowicz continued his remarkable run at the Paris Masters on Friday, reaching the semifinals when eighth-seeded Janko Tipsarevic retired while trailing 3-6, 6-1, 4-1.
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 briefly continued and Janowicz was ahead 40-0 on his serve when Tipsarevic waved his racket to indicate he was stopping, drawing jeers from the crowd at the Bercy Indoor Arena.
Organizers said Tipsarevic, who qualified on Thursday for the season-ending ATP World Tour Finals in London next week, started feeling fatigued at the end of the first set.
The 69th-ranked Janowicz will face Gilles Simon, who is also unseeded, in the semifinals. The Frenchman earlier beat fifth-seeded Tomas Berdych of the Czech Republic 6-4, 6-4.
Later Friday, fourth-seeded David Ferrer was playing No. 6 Jo-Wilfried Tsonga, and Frenchman Michael Llodra was taking on big-serving American Sam Querrey.
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.
Janowicz stepped up his game in the second set, breaking Tipsarevic twice. The 21-year-old did not face a single break point, and held to love on his service game to even 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 a 4-1 advantage.
At the changeover, Tipsarevic appeared to complain of dizziness and stuck out his tongue while a trainer checked his throat.
Simon, meanwhile, fought back from a 4-1 deficit 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 a 4-1 lead.
But Simon earned two straight break points 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.
The momentum started to shift back in Simon's favor after he saved three more break points in the fourth game, preventing Berdych from going ahead 4-0.
Berdych, who converted only one of his 10 break point opportunities, missed another chance in the 10th game when Simon trailed 0-40 as he served for the match.