AceShowbiz - Pop superstar Cher was forced to scrap a recent concert in Las Vegas just moments before she was due onstage after she was struck down with an agonizing stomach bug. The "Believe" hitmaker is in the middle of a three-year residency at Sin City's Caesars Palace, which began in 2008 and will see her perform a total of 200 dates.

But the singer, 64, had to bow out of a show on May 22 when a mystery virus left her doubled over in pain as she was preparing for the gig. A source tells the National Enquirer, "One minute she seemed fine, and she was getting her hair and make-up done in the dressing room. Then, about 20 minutes before the 7.30pm show, she was in so much pain she couldn't stand up. She fell back into her chair clutching her stomach."

Cher resumed her show the following night but the ailing star's pale appearance at the concert sparked fears her health was suffering as a result of her hectic work schedule. However, Cher's publicist has played down the report, claiming the star only suffered a "little infection", adding, "She is in remarkable shape and in excellent health."

Cher has previously fallen victim to stress-related illness Epstein-Barr disease in the 1980s.