Sweden's Robin Soderling served 16 aces as he knocked top seed Andy Roddick out in straight sets in the quarter-finals of the Regions Morgan Keegan Championships.

A finalist in 2006, Soderling did not have to face a break-point against the American - who managed 15 aces of his own at the hardcourt event in Memphis.

"We both served well, and it was fun to play against him," said 23-year-old Soderling after winning his first meeting with Roddick 7-6 (8/6), 6-3.

"This is probably my favourite court on tour. I am serving really well. I think I am playing better and better with every match."

Next up for the Swede in the semi-finals is fourth seed Czech Radek Stepanek, who survived a first-set tie-break en route to a 7-6 (7/4), 6-1 victory over Chris Guccione.

Another Swede, Jonas Bjorkman, also advanced to the semi-finals with a 1-6, 6-2, 7-6 (8/6) victory over American teenager Donald Young.

Unseeded Steve Darcis, of Belgium, needed only 51 minutes to rout Germany's Benjamin Becker 6-1 6-0 and reach his second career ATP semi-final.