Brock Lesnar will face Strikeforce champion Alistair Overeem in a five-round mathchup that will headline a December 30 UFC pay-per-iew event in Las Vegas, the UFC announced on Tuesday.

Lesnar (5-2) last fought at UFC 121 in October losing the heavyweight title to Cain Velasquez, but has since been recovering from a second stint with the digestive disorder diverticulitis. The illness first sidelined him for nearly a year after defeating Frank Mir at UFC 100. He returned to successfully defend his title against Shane Carwin at UFC 116 and went on to coach against Junior Dos Santos in the most recent season of The Ultimate Fighter, but was unable to participate in the culminating fight against Dos Santos in June at UFC 131.

Overeem (35-11-1) won the Strikeforce heavyweight title in November 2007 against Paul Buentello but only defended the belt once, against Brett Rogers, before participating in the Strikeforce Heavyweight Grand Prix, where he won a rematch with Fabricio Werdum in June before being released from the final fight on his contract when he was unable to fight in its semifinals later this month.

By signing with the UFC, Overeem will fight exclusively in the Octagon after having been allowed to fight in other organizations under Strikeforce, notably including kickboxing in K-1.

The Lesnar-Overeem winner will be the top contender to challenge the winner of November’s UFC on Fox main event between the heavyweight champion Velasquez and challenger dos Santos.

The UFC’s traditional New Year’s event will be held on Friday to avoid New Year’s Eve the following night.