Carlos Alcaraz is unsure if he will be fit for the ATP Finals after the world number one retired from the Paris Masters due to an abdominal injury.

The world number one cut short his quarter-final against Holger Rune in the French capital during a second-set tie-break after he lost the opener 6-3 on Friday.

Alcaraz stated after his retirement that it is too early to say whether he will be able to play in the prestigious season-ending tournament in Turin which starts on November 13.

The US Open champion said: "I don't know if I'll make it to the Masters Cup [ATP Finals]. Right now I have to do some tests to see how I am before going to Turin.

"I am focused on trying to improve my abdomen and trying to be 100 per cent in Turin."

The Spaniard felt there was no point in taking any chances.

He added: "At the end of the set, I felt bad. My abdomen was getting bad and I preferred to retire to see it and take care of it.

"I can't stretch. I couldn't serve well, I couldn't hit my forehand and when I turned the body I feel pain, I feel the abdomen in all the movements.

"I was playing thinking about it and feeling the pain, so it was better to withdraw."

Rune will face Felix Auger-Aliassime in his first ATP Masters 1000 semi-final, with both players finishing the season strongly.

Auger-Aliassime beat Frances Tiafoe 6-1 6-4 for his 16th consecutive win to set up a repeat of a final in Basel that the Canadian won last weekend.