MELBOURNE, Australia – Andy Roddick was ruthless, treating his close friend like little more than warmup fodder for his semifinal showdown with Roger Federer.

The 2003 U.S. Open champion flattened Mardy Fish without blinking Tuesday, making only four unforced errors in a 6-2, 6-2, 6-2 quarterfinal win at the Australian Open.

“I played pretty flawless, I thought,” Roddick said. “I feel good going into the semis.”

Roddick said he could remember making more errors in one game than he had in the entire match against Fish, who lived with him in Boca Raton, Fla., and went to his high school.

“I tried my best to kind of put our friendship to the back of my head,” Roddick said. “You know, it’s always difficult. It’s a weird, weird situation.”

Next up is how to beat Federer, something he has not managed since Montreal in 2003.

That was the year he ended at No. 1 and collected his only major title.

Federer also won his first major at Wimbledon that year, and is now bidding for his 10th Grand Slam title.

The defending champion met some tricky wind conditions on Rod Laver Arena and a difficult opponent, looking nervous at times during a 6-3, 7-6 (2), 7-5 win over No. 7 Tommy Robredo with his parents in the crowd.

Federer, who lost to Roddick in the final of an exhibition tournament 10 days ago, dropped his serve four times. He shook his head after shanking some shots.

“The break of serves, they’re due to the wind I assume,” Federer said. “I had to kind of change my game around a little bit midway through the second set.