Melbourne - Defending champion Rafael Nadal needed a hard-fought four-set win over German 27th seed Philipp Kohlschreiber before reaching the last 16 at the Australian Open on Friday.
The Spanish second seed was kept on the Rod Laver Arena centre court for three-and-a-half hours before completing a 6-4, 6-2, 2-6, 7-5 victory.
Nadal will have just a day to recover from the long draining match before taking on his fourth round opponent, unseeded Croatian Ivo Karlovic.
"Well, the most important thing is I won, so I'm happy for that," Nadal said.
"I am less happy about my game, what I was practising. But, yeah, everybody has not very good days.
"I think I played much better the fourth set. The second set for a few moments I played well, too.
"But the first set and the third, I played bad and I need to play a little bit more aggressive for my next match."
Nadal stretched his record over Kohlschreiber to 5-0, but it was his toughest encounter against the determined German, who slugged it out all the way with the world number two.
In the end only eight points separated them over the 38 games.
"If your opponent has confidence and the ball goes in, like few moments today for Philipp, it's difficult to stop," Nadal said.
Nadal broke Kohlschreiber's serve five times from 12 break point opportunities, while the German cracked the Spaniard's serve three times from 15 break point chances.
The Spaniard was made to fight for every set and he capitalised on a service break in the fifth game to take the opening set.
He stretched his lead by taking the second set after service breaks in the first and seventh games, but Kohlschreiber proved resilient and hit back, taking the third set with two service breaks.
Nadal gained an edge with a break in the seventh game of the fourth set, but Kohlschreiber broke back straight away when the Spaniard was serving for the match.
Kohlschreiber was broken a second time in the set when he sent a forehand wide and this time Nadal successfully served out for the match.
Nadal, who conquered Roger Federer over five sets in last year's final, is bidding for his seventh Grand Slam title.
The win Friday improved his Australian Open record to 24-4.
Nadal is expecting a tough time against the big-serving Karlovic in his next match.
"He's always a really difficult opponent because the match is decided on a few points," he said.
"So the thing is to be very concentrated with my serve all the time and try to convert the small opportunities that I have on the return. That's it."
Nadal has won both the two matches he has played against Karlovic.
Karlovic won the all-Croat encounter with 24th-seed Ivan Ljubicic, 6-3, 3-6, 6-3, 7-6 (9/7).
Results from day five of the Australian Open at Melbourne Park on Friday (x denotes seeding):
Andy Roddick (USA x7) bt Feliciano Lopez (ESP) 6-7 (4/7), 6-4, 6-4, 7-6 (7/3)
Fernando Gonzalez (CHI x11) bt Evgeny Korolev (KAZ) 6-7 (5/7), 6-3, 1-6, 6-3, 6-4
Andy Murray (GBR x5) bt Florent Serra (FRA) 7-5, 6-1, 6-4
John Isner (USA x33) bt Gael Monfils (FRA x12) 6-1, 4-6, 7-6 (7/4), 7-6 (7/5)
Juan Martin Del Potro (ARG x4) bt Florian Mayer (GER) 6-3, 0-6, 6-4, 7-5
Marin Cilic (CRO x14) bt Stanislas Wawrinka (SUI x19) 4-6, 6-4, 6-3, 6-3
Rafael Nadal (ESP x2) bt Philipp Kohlschreiber (GER x27) 6-4, 6-2, 2-6, 7-5
Ivo Karlovic (CRO) bt Ivan Ljubicic (CRO x24) 6-3, 3-6, 6-3, 7-6 (9/7)
Dinara Safina (RUS x2) bt Elena Baltacha (GBR) 6-1, 6-2
Alona Bondarenko (UKR x31) bt Jelena Jankovic (SRB x8) 6-2, 6-3
Justin Henin (BEL) bt Alisa Kleybanova (RUS x27) 3-6, 6-4, 6-2
Yanina Wickmayer (BEL) bt Sara Errani (ITA) 6-1, 6-7 (4/7), 6-3
Maria Kirilenko (RUS) bt Roberta Vinci (ITA) 7-5, 7-6 (7/4)
Zheng Jie (CHN) bt Marion Bartoli (FRA x11) 5-7, 6-3, 6-0
Nadia Petrova (RUS x19) bt Kim Clijsters (BEL x15) 6-0, 6-1