Pop princess Kylie Minogue pulled out of a gig in Australia with Irish superstars U2 yesterday (13NOV06) citing exhaustion. The diminutive singer, who has recently won her battle with breast cancer, was joined on stage by Bono last Sunday (12NOV) for an impromptu duet at her Showgirl homecoming tour at the Sydney Entertainment Centre. She was due to return the favour when the VERTIGO hitmakers performed at the same venue yesterday, but the CAN'T GET YOU OUT OF MY HEAD singer cancelled because she was too exhausted to go ahead with the performance. A source close to Minogue says, "Kylie called Bono to explain that she had worn herself out. She is really feeling the physical effects of her return to the stage. He told her to spend Monday resting, get her energy levels fully restored and relax. "It wasn't a problem at all. Everyone realises Kylie is putting herself through the mill for her tour."