Singer Lady Gaga, seen at a New York event in October, told Indiana fans she was devastated at having to postpone Thursday night's concert at the last minute. (Evan Agostini/Associated Press)Chart-topping dance-pop diva Lady Gaga collapsed and suffered breathing problems backstage before a sold-out concert in West Lafayette, Ind., on Thursday night, forcing its postponement.

After opening acts Jason Derulo and Semi Precious Weapons performed, fans gathered at Purdue University's Elliott Hall of Music were informed that 23-year-old Lady Gaga would not take the stage due to "sudden illness."

The singer, whose real name is Stefani Germanotta, later apologized to her fans via her Twitter account.

"Can't apologize enough for how sorry I am," she said.

"I could hear my fans cheering from my dressing room, I begged everyone to let me go onstage."

However, because she had collapsed from exhaustion and dehydration just an hour before, there was concern that the outlandish performer could endanger herself during the complicated two-hour stage show, she revealed.

Paramedics had also been called to the scene and informed her she had an irregular heartbeat, Gaga said.

Doctors have advised the singer to take a few days off to rest. The West Lafayette concert has been rescheduled for Jan. 26.

"I am so devastated," the singer said, adding that the cancellation left her "crying for hours" for letting down her fans.

"I have performed with the flu, a cold, strep throat: I would never cancel a show just based on discomfort ... I hope you can forgive me. I love my [fans] more than anything, you are everything to me."

Lady Gaga's current Monster Ball Tour is slated to end its North American leg in New York on Jan. 24.

She is scheduled to attend and perform at the Grammy Awards in Los Angeles on Jan. 31. She is nominated in five categories.

In February, Lady Gaga will kick off her tour's European run.