WIMBLEDON, England -- Rafael Nadal's bothersome right knee held up fine during a 40-minute practice at the All England Club on Sunday.
Walking briskly while toting his racket bag after his light workout, Nadal told The Associated Press that his knee felt "good, good; not bad."
Toni Nadal, Rafael's uncle and coach, was more expansive, saying, "The knee is so much better" than it was Saturday, when the 2008 Wimbledon champion received treatment from a trainer during changeovers while coming back to beat No. 33-seeded Philipp Petzschner of Germany 6-4, 4-6, 6-7 (5), 6-2, 6-3 in the third round.
That was Nadal's second consecutive five-set victory, the first time he's ever had two matches go the distance this early at a major tournament.
The Spaniard went out to hit early Sunday afternoon during a star-studded training session. Roger Federer was perhaps 20 feet away on the court to Nadal's right, and Andy Roddick was to Nadal's left, while Novak Djokovic and Robin Soderling played a tiebreaker for fun nearby.
After Sunday's day off, Wimbledon resumes Monday with all 16 men's and women's fourth-round matches, and the No. 2-seeded Nadal faces 66th-ranked Paul-Henri Mathieu of France.
"I hope and think he can play with no problem," Toni Nadal said. "We are nervous about the opponent, but not the knee, at the moment."
His nephew's knees have been a long-standing issue.
Rafael Nadal skipped the grass-court Grand Slam tournament last year because of tendinitis in both knees, becoming only the fifth player in the history of an event first contested in 1877 to not defend his championship because of an injury.
He stopped playing during his Australian Open quarterfinal against Andy Murray in January because of trouble with the right knee. And Nadal acknowledged Saturday he's been dealing with knee issues this spring, including during a loss to Roddick at Key Biscayne, Fla., in early April.
"I don't like to say [anything] in that moment," Nadal explained, "because when you lose, [it] always looks like an excuse."
Nadal said he received treatment on his left knee after winning the title on clay at Monte Carlo later in April, but said he did not have time to have the same procedure done on his right knee. He wound up going 22-0 and collecting four titles during the European clay-court circuit, including his fifth French Open and seventh Grand Slam championship overall.
Angel Ruiz Cotorro, a doctor with the Spanish tennis federation who works with Nadal, said Sunday they'll do the new treatment on the right knee after Wimbledon "to improve the regeneration of the tendon."
After watching Nadal practice Sunday, the doctor said the right knee is "better, but we will see tomorrow, in the morning."