Paris (AFP) - World number one Carlos Alcaraz retired from his Paris Masters quarter-final against Holger Rune on Friday with an abdominal injury, while Felix Auger-Aliassime stretched his winning run to 16 matches.
Alcaraz, the reigning US Open champion, lost the first set and was trailing 3-1 in a second set tie-break when he decided to stop, having received treatment to his left side at the previous changeover.
"It's something wrong on the abdominal," said Alcaraz."At the end of the set, it was wrong.It was getting wrong and I preferred to retire and take care about it."
The Spanish teenager had been attempting to win a third Masters title of the year after victories in Miami and Madrid.
Alcaraz would have been confirmed as the year-end world number one before the ATP Finals in Turin later this month had he lifted the trophy this weekend in the French capital.
Instead, his participation at the November 13-20 event is now in doubt.Alcaraz had arrived in Paris struggling with a knee injury, an issue he downplayed earlier in the week.
"Right now I have some test on how it's gonna be before Turin, but right now I'm focused to try to get better in the abdominal and trying to be at 100 per cent in Turin," said Alcaraz.
"I cannot stretch.I couldn't serve well.I couldn't hit the forehand well.When I turn the body, I feel it.I feel the abdomen in so many movements."
"It's in a zone that I have problems, I have problems before," he added."Let's see if it's the same problem as I felt before or not."
Rune will advance to face Auger-Aliassime for a place in Sunday's final.The 19-year-old Dane was beaten by Auger-Aliassime in the final in Basel last weekend.
Auger-Aliassime continued his quest for a fourth title in as many weeks by defeating Frances Tiafoe 6-1, 6-4 to power into the semi-finals earlier in the day.
The 22-year-old Canadian also won in Antwerp and Basel last month.He is trying to achieve a feat no man has accomplished since Ivan Lendl won five tournaments in five weeks in 1981.
Having raced through the opening set against the 21st-ranked Tiafoe, Auger-Aliassime needed six match points to finally see off the American and reach his second Masters semi-final.
The eighth-seeded Auger-Aliassime has enjoyed a breakout season.His 56 wins are third most on the ATP Tour this year, while only Alcaraz has bettered his four singles titles.
"I have felt great not only this week but in the last few weeks," said Auger-Aliassime.
"Sixteen wins in a row is special.I have an opportunity to win again tomorrow.I'll try to seize it, but definitely it's been an amazing period."
Defending champion Novak Djokovic takes on Italy's Lorenzo Musetti in the quarter-finals.
Tommy Paul, who dumped out Rafael Nadal in the second round, will look to cause another surprise when he goes up against fifth seed Stefanos Tsitsipas.
