CHARLESTON, S.C. ? Andy Roddick hit a record 155 mph serve in his 6-1, 6-4, 6-4 win over Vladimir Voltchkov on Friday to help the United States to a 2-0 lead over Belarus in the Davis Cup semifinals.

Olympic silver medalist Mardy Fish served 19 aces to defeat Max Mirnyi in the second match, 7-5, 6-2, 3-6, 6-3.

Roddick’s serve in the final game eclipsed his own record of 153 mph set at the Queen’s Club tournament in England in June. Even with the record speed, Voltchkov managed to get his racket on the ball, but was unable to return it.

“I hit a good one. That’s about it,” Roddick said. “I think it’s fun for the fans. To me it’s still a point.”

Earlier in the match with Voltchkov, who is ranked 162nd in the world, Roddick had serves of 151 and 152 mph.

In the second match, it appeared the momentum was swinging to Mirnyi when he took the third set.

But Fish broke his opponent in the fourth game of the fourth set and then held serve to go up 4-1.

The American team of Bob and Mike Bryan is scheduled to play Mirnyi and Alexander Skrypko today in the best-of-five competition. The reverse singles match is Sunday. In the other semifinal, France led Spain, 1-0, in Spain.