Former UFC interim heavyweight champion Shane Carwin is making his return to mixed martial arts after a five-year absence.
The 41-year-old Coloradan has signed with the RIZIN Fighting Federation and will make his debut in the second round of the company's open weight World Grand Prix tournament in Saitama, Japan, on Dec. 29.
His opponent has yet to be determined.
Carwin, a former NCAA Division 2 wrestling champion, used heavy hands to blitz his way through the UFC's heavyweight division, columinating in a ferocious knockout of Frank Mir to claim the interim title at UFC 111.
From there, Carwin nearly won the title from then-champion Brock Lesnar at UFC 116 before losing in the second round. Injuries hampered Carwin from there, and he only appeared once more, losing to Junior dos Santos at UFC 131 in 2011, before announcing his retirement from the sport.
The opening round of the tournament was held on Sept. 25 in Saitama. Mirko "Cro Cop" Filipovic, Valentin Moldavsky, Amir Aliakbari, Jiri Prochazka, Szymon Bzor, and Baruto all won first-round bouts. Filopvic will be matched up with Wanderlei Silva, who had a first-round bye, on the 29th. The remaining competitors will be matched up at a time to be determined.
The quarterfinal fights will be held on the 29th, with the semifinals and finals being contested two nights later, also in Saitama.
Carwin had hinted at a return on Monday, when he tweeted a picture of a pair of RIZIN gloves, then stated in another tweet he had accepted an offer to fight Fedor Emelianenko.