(CNN) -- Defending champion Rafael Nadal battled through into the last 16 of the Australian Open after being taken to four sets on Friday, while fellow title hopefuls Juan Martin Del Potro, Andy Murray and Andy Roddick also progressed.
World No. 2 Nadal progressed after beating German 27th seed Philipp Kohlschreiber 6-4 6-2 2-6 7-5 in three hours and 39 minutes.
The Spaniard will play Ivo Karlovic in the fourth round after the big-serving Croatian defeated 24th-seeded compatriot Ivan Ljubicic 6-3 3-6 6-3 7-6 (9-7).
Kohlschreiber had eliminated two other left-handers in his opening matches, and fought back to stun an out-of-sorts Nadal by winning the third set.
He fought back from a break down to level at 4-4, but paid the price for three wild forehands on his own serve at 5-5 and Nadal duly closed out the match.
Fifth seed Murray had no such problems as he cruised past Frenchman Florent Serrain with a 7-5 6-1 6-4 victory, and has yet to drop a set in three matches so far.
The 22-year-old Briton will next play American 33rd seed John Isner, with Nadal waiting for him in the quarterfinals if they both win their fourth-round ties.
But he faces a challenge against the big-serving Isner, who knocked out French 12th seed Gael Monfils 6-1 4-6 7-6 (7-4) 7-6 (7-5) and is the second tallest player on tour.
"I have broken serve a lot so far this tournament against guys that have good serves," Murray said. "Kevin Anderson is a good server. I returned well against him. I'm going to need that in the next match.
"Isner is playing really well. He won the tournament in Auckland last week. The guy is 6ft 9in and he has if not the best serve on the tour... I'll have to return well again."
Fourth seed Del Potro was also taken to four sets as he defeated Germany's Florian Mayer 6-3 0-6 6-4 7-5.
The U.S. Open champion will face 14th seed Marin Cilic in the fourth round after the Croatian defeated Swiss 19th seed Stanislas Wawrinka 4-6 6-4 6-3 6-3.
If Argentine Del Potro wins that match, he will play either seventh seed Andy Roddick or 11th seed Fernando Gonzalez in the quarterfinals.
Roddick, the 2007 losing finalist, advanced after being tested by Spain's Feliciano Lopez before he finally won 6-7 (4-7) 6-4 6-4 7-6 (7-3) in three hours and 32 minutes.
Both men recorded 29 aces, but Lopez suffered through 60 unforced errors, while Roddick had 21.
"I felt like I was real close to getting on top of the match and making it, turning it, to kind of make it a little bit more comfortable," the American told the tournament's Web site. "Just didn't quite get there."
Gonzalez was also on court for more than three hours as he edged out Kazakhstan's Evgeny Korolev 6-7 (7-5) 6-3 1-6 6-3 6-4.