MASON, Ohio — Andy Roddick developed back spasms during his opening match at the Western & Southern Open on Tuesday, setting up a two-set loss that left questions about his health heading into the U.S. Open.

Wild card Venus Williams survived a three-set opening match, another encouraging win coming off her Olympic gold medal in doubles with sister Serena.

Later Tuesday, Serena Williams beat Eleni Daniilidou of Greece 6-3, 6-4, overcoming 42 unforced errors as she struggled to get readjusted to a hard court.

Roddick, who has played through a sore shoulder this summer, developed a new concern as he lost to a player who was in the draw as an injury replacement.

He got treatment for his back during the second set of his 7-6 (4), 6-3 loss to France’s Jeremy Chardy, who replaced injured No. 9 seed John Isner. Roddick had won all three of his career matches against Chardy.

Roddick said his back started bothering him a few days ago and he aggravated it Tuesday.

“I felt fine early on, and then I had one lunge forehand and ... you know, we have all had it,” he said. “The back kind of goes out or spasms a little bit. It got progressively worse.”

Roddick won the Atlanta Open in July despite a sore right shoulder. He lost to Novak Djokovic 6-2, 6-1 in the second round at the Olympics, a match that lasted only 54 minutes, but arrived for the tournament in suburban Cincinnati feeling good about his health and his game.

Roddick said his shoulder felt fine. He’s not sure if his back will force him to curtail his preparation for the U.S. Open, which starts Aug. 27.