Rafael Nadal put away Fernando Verdasco 6-4, 6-0 at the Italian Open on Friday, and ought to be a little nervous.

He's conceded only six games in six sets at the Foro Italico, but he's reached the semifinals.

Nadal has fallen in the semifinals of his last three tournaments — all on his favored clay. And next up is Stefanos Tsitsipas, whom Nadal lost to in Madrid last week.

Meanwhile, Roger Federer and top-ranked Naomi Osaka withdrew before their quarterfinals because of injuries.

Federer reported a right leg injury ahead of his match against Tsitsipas, while Osaka said her right hand was hurting before she was to play Kiki Bertens.

Also reaching the last four was Diego Schwartzman, who beat Kei Nishikori for the first time in four tries, 6-4, 6-2, to reach his first Masters Series semifinal.

The 24th-ranked Schwartzman will face top-ranked Novak Djokovic or fellow Argentine Juan Martin del Potro.

While Osaka won both of her matches on Thursday in straight sets, the 37-year-old Federer had to labor for more than 2 ½ hours to overcome Borna Coric in his second time on court.

Federer said after beating Coric that he slid on a wet line and his leg "was hurting a little bit."

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

Later, Federer added on Instagram: "The fan reaction and crowd energy during my matches yesterday remind exactly why I am still competing on the ATP Tour."

It's only the fourth time in Federer's career he has had a walkover loss, the ATP Tour said, adding the 20-time Grand Slam champion has never retired in 1,465 matches.

Osaka couldn't immediately say how serious was her injury, or if it will affect her status for Roland Garros, which starts in nine days. She was yet to see a doctor but when she held her hand up for reporters it was clearly swollen.

"I woke up this morning and couldn't really move my thumb," Osaka said. "I tried to practice and grip my racket but I couldn't, and I kept feeling this pain when I tried to move my hand in different directions."

Osaka's win on Thursday guaranteed she will remain No. 1 going into the French Open.

"I didn't feel anything yesterday. That's why I'm kind of confused right now because I literally woke up in the morning and couldn't move my thumb," Osaka said. "So I was like, 'Maybe I slept on it and maybe it will go away.' But it didn't."

Bertens, who won the Madrid Open last week, will face Marketa Vondrousova or Johanna Konta for a spot in the final.

The quarterfinals in the other half of the draw feature former No. 1 Victoria Azarenka against Karolina Pliskova, and Kristina Mladenovic against Maria Sakkari in a matchup of two qualifiers.

Osaka also withdrew before a semifinal in Stuttgart, Germany, last month due to an abdominal injury. And she retired from her previous meeting with Bertens at last year's WTA Finals with a leg injury.

"I feel like the ab thing could have been helped, but this one I don't think I could have helped it because I don't know what caused it," Osaka said. "I don't know why I have it."