Brock Lesnar, the Ultimate Fighting Championship’s massive heavyweight titleholder, was forced to withdraw Monday from his highly anticipated Nov. 21 title defense in Las Vegas against Shane Carwin.

Carwin, via his Twitter feed, said the fight will be rescheduled for UFC 108 on Jan. 2.

UFC president Dana White confirmed the news to Yahoo! Sports. White said Lesnar has been ill for more than three-and-a-half weeks and unable to train. With the bout at UFC 106 less than a month away, Lesnar was forced to postpone the title defense.

“He said he’s never been this sick in his life,” White said. “He said it’s been going on for a long time and he just hasn’t been able to shake it.”

Lesnar’s co-manager, Brian Stegeman, said he does not know whether Lesnar had H1N1, commonly known as swine flu, and that he is beyond the stage at which he could be tested for the virus. He said Lesnar had upper respiratory issues, fever and extreme fatigue.