MELBOURNE Seventh seed Tommy Haas battered his way past the mercurial Marcelo Rios and into the semifinals of the Australian Open 7-6 6-4 6-7 7-6 on Wednesday.

Former world number one Rios, a runner-up at Melbourne Park in 1998, could not handle the power of the German's lethal serve or backhand.

"My serve was the key I think... Whenever he had some chances to break me my serve saved me," Haas said.

Haas, a losing semifinalist here in 1999, powered through the night match in three hours 17 minutes to set up a semifinal with Marat Safin.

Safin, seeded ninth, earlier reached the last four after just seven games when Wayne Ferreira retired with a stomach strain while trailing 5-2, reported Reuters.

Haas and Rios exchanged early breaks in the opening set but the Chilean grabbed another break in the ninth game with a whipped backhand down the line to give himself the chance of serving for the set.

Haas broke back to stay in the set, however, taking his second break point with a drop volley after forcing Rios out of position.

The pair both held to force a first set tiebreak.

A double fault and a huge backhand gave haas a double break for 5-2 and he chased down a rash drop shot for 6-2 and four set points.

He clinched it on the first when Rios pushed a backhand wide.