Andy Roddick was forced to withdraw from the Madrid Masters on Wednesday because of suffering from a stomach virus.

The fifth seed and world number eight came before his opening match against Madrid's Feliciano Lopez in the second round.

"I was up about 24 hours between Sunday and Monday night with all the symptoms," said Roddick, who won his last event, the Miami Masters, in early April.

"I played doubles Tuesday but couldn't focus on the ball. It was the same this morning after I warmed up.

"This is disappointing. I've worked hard after Miami, spending three weeks on clay in the States with my fitness trainer and coach.

"We'll have to see what I can do to get a match or two," said the player who is due for one exhibition match next week in Paris.