ROME -- Rafael Nadal struggled with a foot injury toward the end of a 1-6, 7-5, 6-2 third-round loss to Denis Shapovalov at the Italian Open on Thursday, while rival and top-ranked Novak Djokovic eased his way into the quarterfinals.
At one point, the 35-year-old Nadal walked over and leaned on his towel box and grimaced in apparent pain. He also limped between points.
Nadal missed a large portion of last year with a left foot injury.
"I hurt my foot again with a lot of pain," Nadal said. "I'm a player living with an injury. It's nothing new. It's something that is there, unfortunately. Day by day is difficult."
It was a worrisome scene for Nadal -- especially with the French Open starting in 10 days.
"What can happen in the next couple of days, I don't know," said Nadal, who has won Roland Garros a record 13 times. "What can happen in one week, I really don't know now."
Nadal returned to the tour last week following a rib stress fracture that kept him out for six weeks after a blistering start to the year that included his record 21st Grand Slam title at the Australian Open.
"It's difficult for me to accept the situation sometimes," Nadal said. "Can be frustrating that a lot of days I can't practice the proper way."
Nadal was also beaten by 19-year-old Carlos Alcaraz in the quarterfinals of last week's Madrid Open.
Nadal double-faulted twice, then missed a backhand long to hand Shapovalov a break of his serve and the second set. Shapovalov then took complete control when he won 14 straight points late in the third.
Nadal said his foot started hurting midway through the second set, adding: "Then [it] wasn't playable for me."
Djokovic was untroubled in a 6-2, 6-2 win over Stan Wawrinka, who was playing only his second tournament after undergoing two surgeries on his left foot.
Djokovic, a five-time champion in Rome, will next play Felix Auger-Aliassime, who ended the run of American qualifier Marcos Giron with a 6-3, 6-2 victory. It will be the first meeting between Djokovic and Auger-Aliassime.
Zverev, who is still seeking his first title of the year, has his father and coach, Alexander, back on the circuit with him after a prolonged absence for reasons the family has kept personal.
When Zverev won the ATP Finals in November, his older brother and fellow pro, Mischa, was coaching him.
"I was missing a coach for six months," Zverev said. "That's what was missing."
The Associated Press contributed to this story.