London:Andy Roddick lost only four points on his serve on Tuesday, beating Radek Stepanek of the Czech Republic 6-4, 6-4 to advance to the third round of the Queen's Club grass-court championships.
The American has lost just one match in his past four appearances at the Wimbledon warm-up event, winning three straight titles before losing to James Blake in the 2006 semifinals.
"That felt really good out there today," Roddick said. "Looking at the draw, there's probably him and Ivo Karlovic as the two guys you don't want to see in the first round."
Roddick served 12 aces and converted his only breakpoint opportunity in the opening set to lead 4-3 after a backhand error by Stepanek.
In the second set, Roddick again set up break point at 3-3 with a forehand pass, but slipped when Stepanek wrong-footed him with a volley at the net.
Roddick eventually broke at 4-4 when Stepanek made two straight backhand errors.
Stepanek twice wanted to challenge a point, but the electronic line-calling system being used on grass for the first time _ Hawk-Eye _ was unavailable due to a power problem.
Roddick had no sympathy for his opponent's frustration.
"It's a machine," he said. "Machines break, right? If it's working, you use it. If it's not, tough stuff."
In the first round, Karlovic beat ninth-seeded Mardy Fish of the United States 6-3, 6-4, with the Croat serving 19 aces.
Also, Sebastien Grosjean of France beat Michael Berrer of Germany 6-4, 6-2, and Jo-Wilfried Tsonga of France beat Kristian Pless of Denmark 7-6 (2), 6-0.
Croatian wild card Marin Cilic beat Tim Henman of Britain 7-6 (5), 2-6, 6-4 for his first ATP Tour victory since July 2006. Henman has won only once on the tour this year.