Carlos Alcaraz says he “preferred” to retire from his Paris Masters quarter-final than risk further damage to an abdominal injury before the ATP Finals.
World number one Alcaraz, 19, was trailing 6-3 6-6 (3-1) to Denmark’s Holger Rune when he had to stop.
“I cannot stretch. I couldn’t serve well, I couldn’t hit the forehand well,” said US Open champion Alcaraz.
Serbia’s Novak Djokovic showed his all-round quality as he beat Italy’s Lorenzo Musetti to reach the last four.
Reigning champion Djokovic, going for a record-extending seventh title, produced what he described as one of his “best matches of the year” to win 6-0 6-3 against 20-year-old Musetti at the indoor event in Paris.
The 35-year-old was already assured of appearing in the ATP Finals because of his status as Wimbledon champion, but this victory ensured he would have qualified as one of the year’s top eight players anyway.
Spain’s Alcaraz is set to make his debut at the season-ending event in Turin next week, which is indicative of his rise over the past 12 months.
He will also be hoping to be fully fit for the Davis Cup Finals, which take place in the Spanish city of Malaga at the end of the month.
“I preferred to retire, see the injury and take care of it,” said Alcaraz.
“I’m focused on trying to get better in the abdominal and trying to be at 100% in Turin.”
Rune, 19, had outplayed Alcaraz before the top seed had to retire, going on to earn a 17th win in his past 19 matches.
World number 18 Rune will play Canada’s Felix Auger-Aliassime – another in-form player – in the semi-finals.
Auger-Aliassime, who has won titles in Florence, Antwerp and Basel recently, extended his winning run to 16 matches after racing to a 6-1 6-4 win over American Frances Tiafoe.
Djokovic faces Greek fifth seed Stefanos Tsitsipas in the other semi-final.
Tsitsipas, 24, advanced with a 6-4 6-2 win over American Tommy Paul, who started a decent week by beating 22-time major champion Rafael Nadal but ended it with a below-par display.
