Roger Federer has withdrawn from the Italian Open in Rome with an injury to his right leg, tournament organisers have confirmed.

Federer, who had been due to face Stefanos Tsitsipas in the quarterfinals, came through two matches Thursday at the rain-affected tournament, beating Joao Sousa in straight sets before being forced to a deciding set against Borna Coric later in the day.

It is that match against Coric that is believed to have caused Federer's injury, with him revealing after the 3-hour, 51-minute contest that he tweaked his leg after slipping on the wet baseline.

The withdrawal is the second of the day, with women's world No. 1 Naomi Osaka withdrawing from her quarterfinal with a hand injury.

"I am disappointed that I will not be able to compete today," Federer said of his withdrawal.

"I am not 100 percent physically, and after consultation with my team, it was determined that I not play. Rome has always been one of my favorite cities to visit, and I hope to be back next year."

With nine days to go until the French Open begins at Roland Garros, it remains to be seen whether Federer's injury is serious enough to throw his participation there into doubt.

The 20-time Grand Slam champion has not played at Roland Garros since reaching the quarterfinals in 2015, with this set to be his return to the clay courts in Paris 10 years after his sole French Open triumph.

With Federer out, Tsitsipas will advance to his third consecutive semifinal after winning in Estoril for his maiden clay-court title before finishing as runner-up to Novak Djokovic in Madrid.