Rafael Nadal, the second seed, set up a quarter-final tie against Andy Murray with a hard-earned win over the Croatian Ivo Karlovic in the fourth round of the Australian Open. Karlovic's compatriot Marin Cilic then took the biggest scalp of the men's draw so far by knocking out the No4 seed and reigning US Open champion, Juan Martín del Potro, in a five-set marathon.
Cilic triumphed 5-7, 6-4, 7-5, 5-7, 6-3 after more than four-and-a-half hours on court. The 14th-seeded Croatian, who had not previously beaten Del Potro and was eliminated by the Argentinian at the same stage of last year's competition, will next face Andy Roddick, who overcame Fernando González in another five-setter.
After beating Roger Federer in the final at the US Open last September, Del Potro was among the favourites in Melbourne, despite carrying a wrist injury. Cilic handed Del Potro the first set after double-faulting on break point but hit back to level the score at 1-1 – at which point Del Potro took a medical timeout for treatment on a foot problem.
The third set lasted for 86 minutes as the two big servers vied for supremacy. Cilic clinched it 7-5 after trading breaks of serve with his opponent but was then broken to love in game 11 of the fourth as Del Potro ensured the match would go the distance. As both 21-year-olds began to tire, it was Cilic who secured the crucial fifth-set break to reach the quarter-finals for the first time.
Nadal faced a tough challenge from the big-serving Karlovic, but eventually overcame his opponent 6-4, 4-6, 6-4, 6-4. Karlovic, with his massive serve, predictably rained down 27 aces on Nadal. However, Nadal was always the classier of the pair, and eventually negated Karlovic's biggest weapon to confirm his match against Murray, who earlier saw off another big server, John Isner.
While Karlovic's serve was daunting at times, Nadal was patient before taking the first set. The Croatian, ranked 39 in the world, upped his game in the second, however, breaking at the first opportunity before going on to seal the set easily. Yet Nadal forced a break early in the third, which was all it took to restore his advantage. Normal service resumed, Nadal was unlikely to let Karlovic back into the match and saw out the fourth set with ease to seal the match.
"I know how tough Ivo is," said Nadal. "If he serves well you can do nothing. I stayed focused and relaxed and tried my best." The world No2 hopes the win will boost his confidence ahead of the showdown with Murray, who is yet to drop a set in the tournament so far. However, Nadal remains acutely aware of the difficulties the British No1 will present him.
"I hope so, I don't know," Nadal said. "Being in the quarter-final is very good for me, it's given me a lot of confidence but I know I have got a really difficult match against Andy. I just wanted to enjoy it today."
"Andy is one of the most talented players on the tour. He can play aggressively, defensively. I will just try to play my game with the forehand and put him a bit behind the baseline, maybe one metre, two metres. If not, maybe I'll have a good flight home!"
In the Rod Laver Arena, Roddick came back from two sets to one down to beat the Chilean González 6-3, 3-6, 4-6, 7-5, 6-2 in a match that finished at gone 1am local time. Roddick, who has never been beyond the semi-finals at Melbourne Park, clinched the deciding set after a double fault by his opponent.
