In a major blow to the Nov. 21 UFC 106 card in Vegas, the heavyweight championship bout between titleholder Brock Lesnar and challenger Shane Carwin has been scrapped.

Yahoo! Sports is reporting that Lesnar withdrew Monday from the main event due to an illness that has sidelined him from training for over three-and-a-half weeks.

"He said he's never been this sick in his life," UFC president Dana White told Yahoo! Sports. "He said it's been going on for a long time and he just hasn't been able to shake it."

At the time of the report, White said he was uncertain if the Lesnar-Carwin fight will be postponed or if Carwin will receive a new opponent on the card.

An hour after the report was published, Carwin said on his Twitter that his manager is telling him that the fight will be postponed until Jan. 2, which is the UFC 108 date at the MGM Grand.

With less than a month away to find a new headliner, the light heavyweight battle between Forrest Griffin and Tito Ortiz could be shifted to the main event.

UFC 106 Fight Card:

Tito Ortiz vs. Forrest Griffin Karo Parisyan vs. Dustin Hazelett Amir Sadollah vs. Phil Baroni Ben Saunders vs. Marcus Davis Kendall Grove vs. Jake Rosholt George Sotiropoulos vs. Jason Dent Luiz Cane vs. Antonio Rogerio Nogueira* Brian Foster vs. Brock Larson* Fabricio Camoes vs. Caol Uno* Paulo Thiago vs. Jacob Volkmann*

*not yet officially announced

SI Apps
We've Got Apps Too
Get expert analysis, unrivaled access, and the award-winning storytelling only SI can provide - from Peter King, Tom Verducci, Lee Jenkins, Seth Davis, and more - delivered straight to you, along with up-to-the-minute news and live scores.