Roddick said he heard a ``clip or pop'' when he landed on the foot at the World Team Cup in Dusseldorf, Germany. He and Massu were tied 2-2 when the injury occurred, and he retired at 2-4 after trying to play with the foot and ankle taped.
``It hurts pretty good,'' he said in a news conference broadcast on the Internet. ``Only time's going to tell.''
No diagnosis of the injury was immediately available.
The French Open, which begins in Paris in four days, already is without eight-time Grand Slam champion Andre Agassi of the U.S., 2004 finalist Guillermo Coria of Argentina and Grand Slam winners Lindsay Davenport and Serena Williams of the U.S.
Agassi said he wants to rest for the grass-court season next month, while the others are injured.
Roddick, the 2003 U.S. Open champion, said he had trouble moving the foot after the injury.
``The next few days I'll be seeing a lot of ice,'' said Roddick, who was hampered by a shoulder injury at the Rome Masters this month. ``I don't know how much court time I'm going to see. So it's going to be days that are pretty boring, full of ice and hope.''
Australian Lleyton Hewitt, a former No. 1 now ranked 14th, twisted his ankle in an opening-round loss at a warm-up in Austria two days ago. He missed last year's French Open with a rib injury.