Top-ranked Jannik Sinner pulled out of the Paris Olympics on Wednesday because of tonsillitis.
The 22-year-old from Italy posted on social media that he was advised by a doctor that he should sit out the Summer Games.
Sinner won the Australian Open in January for his first Grand Slam title and moved to No. 1 in the ATP rankings last month after reaching the French Open semi-finals.
The draw for Olympic tennis is on Thursday. Matches begin on Saturday.
"Missing the Olympics is a big disappointment given that it was one of my main goals this season, Sinner wrote in Italian.
I couldn't wait to have the honour of representing my country in this extremely important event.
