Robbie in rehab.

I wonder if that is part of the reason he had to cancel some shows on his tour.

UK pop star in rehab for drug dependence

LONDON (AP) -- British pop star Robbie Williams has entered rehab in the United States for dependency on prescription drugs, his spokeswoman said Tuesday.

'"Robbie Williams has today been admitted into a treatment center in America for his dependency on prescription drugs," said spokeswoman Bryony Watts. "There will be no further comment on this matter."

Watts didn't identify the clinic where Williams, 33, is being treated.

American model Lisa d'Amato, who says she had a relationship with Williams, was recently quoted as saying the singer used antidepressants.

"It was clear he was struggling with his mind. He doesn't drink, but he needs antidepressants to get him through the day. A lot of the time he seemed on edge," the British Sunday newspaper News of the World quoted d'Amato as saying.'