Josh Hedges/Zuffa LLC.

UFC veteran and former interim heavyweight champion is calling it quits on retirement after a long five years away from the sport.

News announced late Wednesday night of October 26, Shane Carwin has signed with RIZIN FF of Japan. He will make his debut at the end of the year in the second round of the open weight World Grand Prix tournament in Saitama, Japan.

Carwin made his name with his heavy punching power by ending fights in just minutes. Putting Frank Mir’s lights out in under four minutes to claim the UFC interim-heavyweight championship, which he later lost in a unification bout with Brock Lesnar.

Carwin, now 41, enters the Grand Prix tournament with the likes of Mirko Cro Cop and Wanderlei Silva, among others. Cro Cop and Silva will meet in the quarterfinals held on the 29th of December in Saitama, Japan.

An opponent has no yet been determined for Shane Carwin but stay tuned.