It's a major setback for Britney Spears, just hours after she performed a special concert in San Francisco on Good Morning America.
No word on why Iglesias may be withdrawing from the tour, but it comes after the website thedailybeast.com quoted a source saying that Spears appeared "out of it" on a recent episode of Glee.
"They led her to her mark and she'd sit there like a deer in the headlights until she had to say her lines," the source says. "When she was finished, they'd take her by the hand and lead her away again."
On Good Morning America, Spears glittered in silver and blue sequins, then performed another number in a sexy black leather bustier.
Fans lined up around the block for the free concert. Spears released her new album Femme Fatale on Tuesday.
Now Spears's concert tour may be in shambles.