Defending champion Andy Roddick progressed to the quarter finals of the Brisbane International after producing a dominant performance to beat Alexandr Dolgopolov 6-4 6-1.

18936 - Roddick overcomes slow start to advance to last 8

Roddick took time to find his feet, falling behind a break early on, before slipping through the gears to break his opponent twice in each set.

Spurred on by the fact he is donating $100 to the Queensland Flood Relief Appeal, Roddick put everything behind his serve and was rewarded by racking up no fewer than 15 aces - taking his tally for the week to 20.

The No. 2 seed afterwards admitted he had not been surprised by Dolgopolov's ability to hit a string of winners, with the American happy to have employed a successful gameplan.

"The scouting report was that he was aggressive to the point of psychosis at times. He came out the first six games and I didn't really do much wrong," Roddick said.

"If someone decides that they're going to try to hit a winner from whatever ball they get on the first shot, if they convert there's only so much you can do. It was my plan to make him have to come up with those kinds of shots for the better part of a couple of hours and it caught up to him a little bit. Then when it caught up to him it got away from him pretty quickly."

Next up for the world No. 8 is fifth seed Marcos Baghdatis, who thrashed Lukasz Kubot 6-2 6-2 in a little over an hour. Germany's Florian Mayer booked his place in the last eight courtesy of a 6-4 4-6 6-4 triumph over qualifier Richard Berankis. Fernando Verdasco's conqueror Benjamin Becker could not reproduce his heroics as he lost to Colombian Santiago Giraldo.