Andy Roddick put on a brave face but admitted he was left searching for answers after suffering another grand slam disappointment at Melbourne Park on Sunday.

Roddick slumped to a 6-4 1-6 6-3 6-4 fourth-round Australian Open defeat at the hands of talented Cypriot Marcos Baghdatis, extending the 2003 US Open champion's title drought to nine majors.

"It's always tough, but the good thing about tennis is there's always next week. We're not (just) an Olympic sport where we have to wait another four years," the vanquished American said.

"You try to be optimistic right now. It's tough. It's disappointing. But you move on."

But Roddick was left scratching his head after winning more points in the match and having also completed a perfect preparation for the tournament with success at the Kooyong Classic warm-up event.

"I don't know if it's as easy just to shrug off. It's disappointing when you feel like you've put in the work. There are no unanswered questions in my eyes as far as preparation and stuff like that," he said.

"So you're kind of left searching a little bit. That's an uneasy feeling.

"I didn't play that badly. Most times when you lose, you don't have your stats plus eight or whatever I was, as far as winners to errors.

"The guy you're playing against, you hope he doesn't have plus 32 or whatever.

"I looked and I actually won more total points, which is disappointing. I think I would have beaten most people today.

"But let's give credit where credit's due. I thought he played a very good match."

The match of his life in fact.

The former world junior champion countered 26 unforced errors with 63 winners to blunt Roddick's power game and reach the quarter-finals of a grand slam for the first time in his career.

"A lot of winners he hit were from passing shots behind the baseline," Roddick lamented.

"A lot of times I was in control of the point and he came up with the goods."

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