George Michael was due to perform with Alicia Keys tonight (June 15) at the Keep A Child Alive Black Ball, but has been forced to pull out after developing serious problems with his teeth. 

He first informed fans of the growing issue on June 13 when he wrote on Twitter that he noticed "some kind of infection" in his lower jaw that caused his face to swell, but confirmed earlier this afternoon that he's had to withdraw completely:

"This tooth ain't getting better in time for tonight, not enough to sing anyway..... :( I'm really sorry folks. You watch, it'll be totally fine by tomorrow. Bloody typical. I hope not too many of my lovelies managed to grab a ticket :("

The event, which will take place at Camden's Roundhouse, was set up to raise money for families affected by AIDS and Keys will headline later after the crowd enjoys performances from Tinie Tempah and Paloma Faith. 

Watch Michael perform 'True Faith' here: