The organization has released its heavyweight champion, MMA Fighting confirmed with multiple sources close to the fighter, including his trainer Martijn de Jong. HDNet first reported the news on its Inside MMA program Friday night.
Overeem had one fight left on his current contract. He was not immediately available for comment. When contacted by MMA Fighting, Strikeforce officials would not confirm or deny Overeem's departure from the organization.
The news comes on the heels of the announcement that Overeem was removed from the Strikeforce heavyweight grand prix last week after he told Zuffa he wouldn't be ready to fight Antonio Silva in the semi-finals on Sept. 10 due to scheduling and multiple injuries.
"He went into the fight with Werdum with a broken toe and elbow and rib issues, which got worse after the fight," de Jong said on Friday. "He needed to heal up those injuries first to be able to train again."
Overeem explained to MMA Fighting his take on the scheduling issue in a recent interview.
"Strikeforce promised me a date in the fall (October/November), I acted on it and chose to go on holiday and start my training in August," Overeem explained to MMA Fighting via e-mail. "Zuffa/Showtime then decided to do it in September and then the ball was in my court, and I had to decline because I know it's too short of time to be prepared 100 percent Instead of postponing the event they decided that the show must go on and use one of the alternates."
In an earlier interview on The MMA Hour, Overeem said that he felt disrespected by the promotion.
"For them to unilaterally declare, okay, [September 10] is going to be the second round, which I never agreed on, and then threaten me if I don't want it, it ... doesn't really show a lot of respect," he said.
"The thing is, there's other promotions. There's other stuff I can do. K-1's going to come back. There's some good reports on that. There's some other promotions in the world that would love to have me fight. So for me, the respect thing is definitely a factor and it's definitely important."
On Wednesday, Glory World Series announced that "The Reem," who had a non-exclusive contract with Strikeforce, would compete on their upcoming show in October. No opponent or date was announced for the event.
Overeem made his Strikeforce debut in June 2006, defeating Vitor Belfort via unanimous decision. He won their inaugural heavyweight title in November 2007 when he defeated Paul Buentello in the second round.
It would then take Overeem almost three years to return to the organization. He defeated Brett Rogers in May 2010 via impressive first-round TKO. The 31-year-old's last fight in the promotion took place last month in Dallas when he defeated Fabricio Werdum via unanimous decision.