Ultimate Fighting heavyweight champion Brock Lesnar’s fight career could be in jeopardy due to an intestinal illness that will require surgery, according to mixed martial arts impresario Dana White.

White, president of the UFC, told the TMZ website yesterday that Lesnar was “very, very sick” with an intestinal disorder that will require surgery, and that he will try to get the beefy 32-year-old admitted to Minnesota’s Mayo Clinic. White said Lesnar, who was diagnosed with mononucleosis earlier this month, collapsed a week ago while resting at his Canadian vacation property and has since been hospitalized.

“There’s a possibility Lesnar will never fight again,” White told TMZ. Lesnar, who is six-foot-three and 265 pounds and has an outsized personality to match, has not been heard from for three weeks. He was to defend his heavyweight belt in January against Shane Carwin, but that bout, already rescheduled once before amid rumours that Lesnar had contracted the H1N1 virus, has again been put off.

“He’s got mono and he’s got something else wrong with him,” White said Saturday after UFC 105 in England.

“I know what’s wrong with him, he just doesn’t want me talking about it. He doesn’t have cancer or AIDS or anything like this, (but) he’s got some problems, man.”