He was broken again in the fourth game of the second set and soon had to watch Djokovic dish up a pair of aces to open up a two-set advantage.

BBC: Roger Federer & Novak Djokovic progress at Aussie Open

Although there were times when the three-time Australian Open champion could only stand and watch the aces go by or send a drop shot return into the net, he largely had an answer for everything Roddick could send his way.

CNN: Superb Federer crushes Roddick in semis

The Serbian, beaten by Murray to lose his U.S. Open crown last month, converted all four of his break points and fired 12 aces in a near flawless display.

CNN: Murray and Djokovic reach semifinals in Beijing and Tokyo

During that time, Karlovic had sent down 78 aces, 23 more than his previous record in losing in this year's French Open first round to Lleyton Hewitt.

BBC: Spain and Czechs through to final

Roddick hit back with 15 aces and 47 winners but Cilic, who took the scalp of U.S. Open champion Juan Martin Del Potro in the previous round, sealed his 10th win from 10 matches of 2010 to reach his first grand slam semifinal.

CNN: Tennis: Nadal injured, Murray into semis

The last time the 29-year-old, eyeing a fifth title in Melbourne, failed to reach the quarter-finals in a Grand Slam was at the 2004 French Open, and all went to plan with a comfortable first set, starting in blistering style with three aces.

BBC: Roger Federer & Novak Djokovic progress at Aussie Open