Lady Gaga's Poker Face was the best-selling UK single of 2009
Singer Lady Gaga has apologised to fans after being forced to cancel a concert in Indiana due to ill health.
"Can't apologise enough for how sorry I am," she said, via micro-blogging site Twitter, revealing she had collapsed due to exhaustion and dehydration.
"An hour before the show I was feeling dizzy and having trouble breathing," posted the 23-year-old, renowned for her flamboyant stage performances.
She has since cancelled another three dates between 16-18 January.
Last year Lady Gaga - real name Stefani Joanne Angelina Germanotta - failed to appear as a support act at two Take That concerts in Manchester, citing ill health.
The singer tweeted that she had been "crying for hours" as a result of Thursday's cancellation.
"My stage has complicated mechanical elements," she said. "Everyone was concerned I'd be in danger during the 2hr show, since I had passed out earlier.
"I have performed with the flu, a cold [and] strep throat," she went on. "I would never cancel a show just based on discomfort.
"I hope you can forgive me. I love my little monsters more than anything, you are everything to me."
Lady Gaga - who recently topped the UK singles chart with Bad Romance - had the best-selling UK single of 2009 with Poker Face.
Her tour is due to hit the UK in Manchester on 18 February.