UFC heavyweight champion Brock Lesnar has withdrawn from his upcoming title defense against Shane Carwin
because of an illness.

Lesnar was scheduled to fight Carwin in the main event of UFC 106 on Nov. 21 at the Mandalay Bay Events Center in Las Vegas. The former professional wrestler and college wrestling champion said Monday he's been out of training for nearly a month while battling the unspecified illness.

Lesnar is the mixed martial arts league's top pay-per-view draw after his lucrative title defense against Frank Mir in UFC 100.

Tito Ortiz's return to UFC against former champion Forrest Griffin will become the main event at UFC 106.

UFC hopes to reschedule Lesnar's fight against the unbeaten Carwin for early next year.