LONDON -- On a day Novak Djokovic advanced easily in three sets, fourth-seeded
David Ferrer came from a set down twice to reach the fourth round at Wimbledon, wearing down Alexandr Dolgopolov of Ukraine 6-7 (6), 7-6 (2), 2-6, 6-1, 6-2 on Saturday.
In a back-and-forth match on Court 1, Ferrer needed treatment for blisters on his foot but still managed to outlast the 26th-seeded Dolgopolov and reach the last 16 for the fourth year in a row.
He reached the quarterfinals last year and is coming off his first career Grand Slam final at the French Open.
Dolgopolov was trying to become the second Ukrainian man to reach the fourth round at the All England Club after Andrei Medvedev in 1994.
Djokovic, the No. 1 seed, reached the next round after cruising by Jeremy Chardy 6-3, 6-2, 6-2. Djokovic avoided further upsets after seven-time champion Roger Federer and Rafael Nadal were eliminated early.
"Everything went my way," Djokovic said. "I did everything I wanted to do. ... When you play that well, obviously you feel great, you feel confident. This kind of performance came in the right time for me."
Tomic, who in 2011 as an 18-year-old qualifier became the youngest Wimbledon quarterfinalist since Boris Becker in 1985, advanced to the fourth round with a 7-6 (7), 5-7, 7-5, 7-6 (5) win.
Del Potro hurt his left leg when chasing down a drop shot in the third set, skidding awkwardly on the grass and tumbling face first. He received treatment after taking a 4-0 lead and took a medical timeout after the next game, and returned to break Zemlja again to clinch the win.
Del Potro said he twisted his ankle and hyper-extended his knee and will need to consult a doctor.
The Argentine said "it was really painful. I was a little scared at that moment. ... Now I start to feel something in my knee and my ankle, as well. I will check with the doctor very soon."
Because of rain over the last two days, Wimbledon organizers were playing a bit of catch-up with the schedule on Saturday before Sunday's rest day.
Among several other matches that had been postponed, No. 20 Mikhail Youzhny of Russia beat Viktor Troicki 6-3, 6-4, 7-5 to set up a fourth-round meeting with second-seeded Andy Murray, who won in straight sets on Friday.
Two other seeded players went out against unseeded opposition, as No. 22 Juan Monaco of Argentina fell 6-4, 7-6 (8), 6-4 to Frenchman Kenny De Schepper, while No. 26 Benoit Paire of France lost 6-1, 6-3, 6-4 to Lukasz Kubot of Poland.
No. 23 Andreas Seppi of Italy kept up his perfect record in five-set matches in 2013, winning his seventh straight by defeating 12th-seeded Kei Nishikori of Japan 3-6, 6-2, 6-7 (4), 6-1, 6-4. Seppi also beat Denis Istomin in five sets in the first round, and won two five-setters each at this year's Australian Open and French Open. He also rallied from two sets down in a Davis Cup match this year.
Information from The Associated Press was used in this report.