WIMBLEDON, England -- Things got quite complicated for Rafael Nadal on Saturday.
His right knee was bothering him "a lot," something he later would say he's "a little bit scared about." His left elbow was briefly in pain, too, following one serve.
He got into a dispute with the chair umpire over whether Toni Nadal, Rafael's uncle, was coaching during the match, which is against the rules.
Oh, and then there was this issue, of most immediate concern Saturday: For the second consecutive round at Wimbledon, Nadal fell behind by two sets to one.
For the second consecutive round, though, the generally indefatigable Nadal came back and came through, this time pulling out a 6-4, 4-6, 6-7 (5), 6-2, 6-3 victory over 33rd-seeded Philipp Petzschner of Germany to reach the second week.
"This match was very difficult for me," Nadal acknowledged. "Having a five-set match two days ago and one today -- that's tough. I'm happy to be in the fourth round. I'm going to try to be better for Monday."
That's when the grass-court Grand Slam tournament will resume after observing its traditional day of rest on the middle Sunday, all 32 players still in the event will be on the jam-packed schedule.
Nadal will meet 66th-ranked Paul-Henri Mathieu of France, who beat Thiemo de Bakker of the Netherlands 7-6 (5), 7-6 (6), 6-7 (8), 6-4. In his previous outing, de Bakker eliminated John Isner, the 6-foot-9 American who won the longest match in tennis history, 70-68 in the fifth set.
Isner was still in town Saturday morning, having breakfast in Wimbledon village with doubles partner and pal Sam Querrey. Hours later, as darkness descended, No. 18 Querrey won his own lengthy -- well, not THAT lengthy, of course -- match, reaching Wimbledon's fourth round for the first time by defeating 2002 semifinalist Xavier Malisse of Belgium 6-7 (4), 6-4, 6-2, 5-7, 9-7. The final point was played at 9:23 p.m., and Querrey figured the match would have been suspended and continued Monday if he hadn't won when he did.
Next up for Querrey, a 22-year-old from Santa Monica, Calif., is a Centre Court contest against No. 4 Andy Murray, trying to become Britain's first Wimbledon men's champion since Fred Perry in 1936.
"I think it'll be 99 percent for Murray," Querrey said, "and, like, my mom and dad and sister cheering for me."
Murray, who hasn't dropped a set so far, beat No. 26 Gilles Simon of France 6-1, 6-4, 6-4 Saturday.
Other fourth-round men's matches Monday will include two-time French Open runner-up Robin Soderling of Sweden vs. No. 9 David Ferrer of Spain, and No. 10 Jo-Wilfried Tsonga vs. No. 32 Julien Benneteau in an all-French pairing.
Neither of those is nearly as intriguing as the women's matchup between 12-time Grand Slam champion Serena Williams and three-time major winner Maria Sharapova. It's a rematch of the 2004 Wimbledon final, which Sharapova won, but Williams leads their career series 5-2.
"I love going on the court and playing someone that's obviously the favorite," Sharapova said.
She struggled at the start of her 7-5, 6-3 victory over 68th-ranked Barbora Zahlavova Strycova of the Czech Republic. Defending champion Williams, in contrast, overwhelmed 46th-ranked Dominika Cibulkova of Slovakia at the outset of what would become a 6-0, 7-5 victory. Williams hit 19 aces and afterward declared: "For the most part my serve works when I'm in trouble. At Wimbledon it works the whole match."
Other women's fourth-round matchups include No. 3 Caroline Wozniacki vs. Petra Kvitova; No. 7 Agnieszka Radwanska vs. No. 9 Li Na; and qualifier Kaia Kanepi vs. Klara Zakopalova.
None of the day's developments, however, was as significant as what happened while Nadal faced Petzschner, who lost in the first round at both of the year's first two major tournaments.
Nadal has won seven Grand Slam titles, including at the French Open this month, and never before has he won two five-setters en route to a major's fourth round. But the Spaniard went the distance against 151st-ranked Robin Haase of the Netherlands on Thursday, then did so again Saturday.
At four separate changeovers, Nadal was visited by a trainer, who mostly worked on the player's right knee. Tendinitis in both knees forced Nadal to pull out of Wimbledon a year ago instead of defending his 2008 title, and he disclosed for the first time Saturday that he's been dealing with knee issues this season.
Nadal said he received "new treatment" that helped his left knee after winning a clay-court title at Monte Carlo in April, but did not have time to get the same work done on the right side. Asked to describe the treatment, he said, "I can't explain (it) now, especially in English. Sorry."
He'll skip Spain's Davis Cup quarterfinal against France on July 9-11 so the same procedure can be carried out on his right knee, because he wants to be healthy in August for the U.S. Open, the only major title missing from his resume.
As for how the knee might effect him at Wimbledon, Nadal said: "I hope I'll be fine. I don't know. I'm going to check."
The left-hander was worried momentarily when he felt something in that elbow, but said that went away quickly and declared, "The arm is perfect."
Petzschner, playing his third five-setter in a row, sought help from a trainer for a recurring hip problem and faded late. He wondered aloud about how much medical help Nadal really needed Saturday, saying there didn't appear to be a difference in the No. 1-ranked man's movement before and after the trainer's visits.
"I only could say if I would be injured like this once, I would be happy. I don't know; maybe he had something. Maybe it was just ... clever ... to take a timeout there."
Nadal denied there was gamesmanship involved.
"I never call the physio when I don't have (anything wrong) -- not one time in my career," he said. "If I (called) the physio today, it was because it was bothering me a lot, the knee."
Chair umpire Cedric Mourier warned Nadal during the fifth set about getting in-match coaching from his uncle, seated in the front row of the player guest box. Rafael Nadal pointed angrily at the umpire, spread his arms wide and shouted at him before returning to action.
Both Nadals said there was no coaching going on.
Instead, Toni Nadal explained, he was telling his nephew to stay positive.
"Nothing else," Toni Nadal said.
If anything, the admonishment from Mourier appeared to spur on the younger Nadal, who reeled off the final three games of the match. After starting only 1 for 11 on break points, he went 3 for 3 down the stretch -- and in sports, of course, all's well that ends well.
"Very difficult," Toni Nadal said, echoing his charge's phrase. "But at least Rafael won the match. So all is OK."
SERENA WINS EASILY, SETS UP SHOWDOWN WITH SHARAPOVA:
Defending champion Serena Williams put on a serving clinic Saturday, hitting 20 aces in a straight-sets win over Dominika Cibulkova that sets up a possible fourth-round matchup with former champion Maria Sharapova.
The top-seeded American had at least two aces in each of her eight service games and overpowered the 46th-ranked Slovak 6-0, 7-5 on Centre Court.
"Serving that well feels awesome," Williams said. "I serve well at Wimbledon for some unknown reason. I want to keep doing it. I wish I could serve like this every tournament."
Williams won 37 of 43 service points and held at love five times. She won 19 of her first 20 service points, with Cibulkova putting only four returns in play in that stretch.
The first set lasted just 18 minutes, with Williams winning 25 of 31 points, serving six aces and hitting 12 winners. It was the third match in a row that Williams won the first set 6-0.
Cibulkova, a semifinalist at the French Open last year, finally got on the scoreboard when she held serve for 1-1 in the second set. From then on, she kept the match competitive by holding serve, although she couldn't cope with Williams' serves.
Cibulkova saved a match point while serving at 4-5 with a crosscourt backhand winner, but Williams broke in the 12th game to close out the match.
Williams credited Cibulkova with raising her game, but was unhappy with her own performance in the second set.
"I just kind of came off the gas a little too much," she said. "Just can't do that in big Grand Slams like this."
Cibulkova -- generously listed at 5-foot-3 -- looked tiny next to the imposing 5-foot-9 Williams.
"It was really hard returning her serve because she was mixing her serve and playing really fast serves to the lines," she said. "I couldn't even get the ball, not even try to hit a return.
"I really doubt if somebody can beat her here if she plays like this."
Williams, chasing her fourth Wimbledon title and 13th Grand Slam crown, will next play the winner of the match between Sharapova and Barbora Zahlavova Strycova. Sharapova beat Williams in the 2004 final, and is coming back into top form after right shoulder surgery in 2008.
Because Sharapova is seeded 16th, the two are meeting in the fourth round rather than the later stages.
"I definitely don't think it's early," Williams said. "It is what it is. You always have to be ready. She's obviously really good, especially on grass."
Recalling the 2004 final, Williams said, "I just remember I was really nervous. I think I put too much pressure on myself. It didn't work out. That was that."
Despite her easy run through the first three rounds this week, Williams doesn't feel as if she's playing as well as last year when she beat sister Venus in the final.
"I definitely have to pick up and play better," she said.
Also Saturday, third-seeded Caroline Wozniacki made it to the fourth round by beating Anastasia Pavlyuchenkova 7-5, 6-4. She'll face unseeded Czech Petra Kvitova, who upset 14th-seeded Victoria Azarenka 7-5, 6-0. Seventh-seeded Agnieszka Radwanska advanced with a 6-3, 6-1 win over Sara Errani of Italy.
In men's play, sixth-seeded Robin Soderling beat the 24th-ranked Thomaz Bellucci 6-4, 6-2, 7-5, his third straight victory without losing a set.