(CNN) -- Rafael Nadal will meet Andy Murray in the quarter-finals of the Australian Open after beating Ivo Karlovic 6-4 4-6 6-4 6-4.
The Spaniard faced a tough challenge as Karlovic, known for his big serve, rained down 28 aces during the match, compared to Nadal's two.
However, the world No.2 showed his class by only committing 15 unforced errors, compared to the Croatian's 42.
Murray earned his match with Nadal after earlier defeating John Isner 7-6 6-3 6-2.
"Murray is very good, he's one of the most talented players on tour," Nadal told the Australian Open Web site when quizzed about their upcoming meeting.
"He can play offensive, he can play defensive. He can do a lot of things during the same match ... He's a very important player."
On Saturday, Roger Federer booked his place in the last 16 of the Australian Open after a routine straight sets win over Spain's Albert Montanes to set up a match with home favourite Lleyton Hewitt.
The world number one was relatively untroubled as claimed a 6-3, 6-4, 6-4 victory over Montanes and felt his serve proved to be crucial factor in the victory.
"I thought it was dominated from my side with my serve, which allowed me then to take chance on the return," Federer told the Australian Open Web site.
"It was a pretty straightforward match, really. I don't remember him having any breakpoints. He was playing tough from the baseline and making it hard. I'm happy with the match and was able to serve it out, so it was good."
Federer will now turn his attention to Australian Hewitt who led Marcos Baghdatis 6-0 4-2 before the Cypriot was forced to retire with a shoulder injury.
Third seed Novak Djokovic thrashed Denis Istomin 6-1 6-1 6-2, while sixth seed Nikolay Davydenko claimed a 6-0 6-3 6-4 victory over Juan Monaco.
Davydenko's fourth-round opponent will be Spaniard Fernando Verdasco, who advanced when Stefan Koubek of Austria retired due to sickness after losing the first set 6-1.
France's Jo-Wilfried Tsonga, who was a beaten finalist in 2008, came from a break down in the fourth set to beat Tommy Haas 6-4 3-6 6-1 7-5.