UFC heavyweight champion Brock Lesnar was sidelined indefinitely foran undisclosed illness. It is now announced that Lesnar is likely to require major surgery and may never fight again according to UFC President Dana White.

According to White, Lesnar, who is also suffering from mono, has been hospitalized since collapsing during a trip to Canada last week. He will be transferred to the Mayo Clinic, where he will undergo surgery for a intestinal disorder.

The illness may jeopardize Lesnar’s UFC career, but the illness can be treated with antibiotics and is not life threatening.

Lesnar was scheduled to fight Shane Carwin this Saturday at UFC 106, but withdrew from the bout last month before before targeting a January return, which again was postponed.

If Lesnar does require surgery and remains out for the foreseeable future, an interim heavyweight title matchup between Carwin and Cain Velasquez is likely to take place in February or March.