Carlos Alcaraz's fitness for his next match at the ATP Finals is in doubt after he abruptly stopped a practice session on Tuesday.
Alcaraz played Casper Ruud in his opening match on Monday. He lost 6-1, 7-5 to the 2022 ATP Finals runner-up, including uncharacteristically blowing a 5-2 lead in the second set.
Although Ruud deserves credit for his performance, Alcaraz struggled throughout the contest. The Spaniard picked up an illness before the tournament began, and that issue remained against Ruud.
Reports before the ATP Finals indicated that Alcaraz trained with a nasal strip to try and improve his breathing during a practice set with Taylor Fritz. The American won the set 6-3.
Alcaraz is scheduled to face Andrey Rublev on Wednesday. Rublev also lost his opening match of the ATP Finals, meaning a win is essential for each man to keep their qualifying hopes alive.
However, the four-time Grand Slam champion's chances of being ready to compete against Rublev could be in doubt after Alcaraz ended his training session on Monday much earlier than expected.
Andres Martin, the current world No. 557, is on-site at the ATP Finals as a practice partner for the players. The American was undoubtedly excited to have a chance to hit with someone of Alcaraz's class.
After coming onto the court shortly after his scheduled time of 11:30 a.m. in Turin, Alcaraz started by hitting at a gradual pace with Martin, which is normal to get warmed up and into a rhythm before becoming more intense.
But Alcaraz did not raise his speed or intensity as the minutes ticked by. Although there was no visible injury problem, the world No. 3 did not try to increase his level close to what he is normally capable of.
Ten minutes later, Alcaraz stopped and sat down. It was not immediately clear that the session would stop, but the 21-year-old's team members gathered around him and started having serious discussions with him.
Shortly after, Alcaraz's coach, Juan Carlos Ferrero, shook hands with Martin. The American looked confused at first, but it quickly became apparent that the Spaniard felt he could not continue.
Alcaraz shook hands with Martin after Ferrero before briefly waving to the crowd as he walked off. The two-time Wimbledon winner did not stop to take pictures or sign autographs for any of the fans and looked disappointed as he left the court.
It is impossible to know precisely what Alcaraz's problem is until he confirms it himself. The illness that bothered him is one possibility, especially since there did not seem to be an obvious injury issue.
Although the ATP Finals is a significant tournament, Alcaraz also wants to be at 100% for the massive occasion of Rafael Nadal's final professional appearance at the Davis Cup Finals in Malaga next week.
Alcaraz will consider his own ambitions when deciding whether to play against Rublev, but the world No. 3's immense respect for Nadal means not jeopardizing being ready for the 22-time Grand Slam champion's farewell could also be a factor in his decision.