Britney Spears had the "most personal and emotional situation" so far during The X Factor audition in San Francisco yesterday.

The pop princess was sat with fellow judges Simon Cowell, L.A. Reid and Demi Lovato when she saw a familiar face at the Oracle Arena.

Sources told People magazine that Britney "recognised him straight away" and "got this huge smile on her face and her eyes lit up."

"I know him," Britney said of the male contestant whose identity has not yet been revealed. "We did a duet together 10 years ago."

The audience became emotionally charged when the man started to cry and told the audience that he was "gay."

"At the time I didn't think I was worthy," he told Britney. "I didn't think you thought it was okay that I am gay."

Britney told him that she thought it "is fine you are gay" and he "started crying and saying he thought he'd never see her again."

"She handled it unbelievably well and really stepped up to the situation," the source added. "It was probably the most personal and emotional situation for her that's happened so far on X Factor, and she took it totally in her stride in front of a live audience of thousands."