Lance Armstrong has pulled out of the 2010 Circuit de la Sarthe race in western France before the second day because of an illness.

The seven-time Tour de France champion, who was looking forward to Wednesday's time trial, was suffering from diarrhea, vomiting and a fever, Team RadioShack spokesman Philippe Maertens said.

"It's really bad, believe me," Maertens said by phone.

The team released a statement Wednesday saying Armstrong had come down with a "viral intestinal infection" - or stomach flu - after the first stage Tuesday.

"He will return to the US as soon as his condition allows," the statement said.

Overnight, Armstrong wrote on his Twitter page: "Sicker than a dog now. This sucks."

The American, who was riding in the four-day race as part of his preparation for the Tour de France in July, had previously tweeted that several of his eight teammates who rode in Sunday's Tour of Flanders had caught "a stomach bug."

The race was Armstrong's first competition in mainland France this year and he was 29th overall after the first stage on Tuesday, won by Team Caisse d'Epargne's Luis Leon Sanchez.

"Lance was really keen on performing well, especially in the time trial of Wednesday afternoon," said Team RadioShack sporting director Alain Gallopin in the statement. He said Armstrong showed improvement at the Tour of Flanders.

Team RadioShack announced Tuesday that Armstrong would not compete as previously planned in the Amstel Gold race on April 18, and he will return to the United States after the Sarthe race.

Maertens said Armstrong wanted to spend time with his family and felt fit enough to prepare at home. He plans to ride in the 2010 Tour of California in May before returning to Europe for the 2010 Dauphine Libere or the 2010 Tour of Switzerland in June.