MELBOURNE (AFP) - Defending champion Stan Wawrinka reached the fourth round of the Australian Open with a straight sets win over Finland's Jarkko Nieminen on Saturday.

The Swiss fourth seed cruised through 6-4, 6-2, 6-4 in 1hr 49min on Rod Laver Arena and will play Spain's Guillermo Garcia-Lopez in the round of 16.

Wawrinka was always in control of his first match with the 72nd-ranked Finn in four years and broke Nieminen's serve six times and hit 55 winners.

Wawrinka, who is now the main Swiss contender at this year's Open following Roger Federer's shock defeat to Andreas Seppi on Friday, was pleased with his progress at the tournament.

"I'm really happy with my game so far, I think today was a really good match," he said.

"I was aggressive on the court, it was in quite fast conditions and I took control of the match.

"It's been three really good matches, I think my game is there and I'm really happy to get through again." Wawrinka said he was looking forward to playing Garcia-Lopez after a "tough loss" to him in the fourth round at last year's French Open.