It’s do-or-die for Alistair Overeem against Frank Mir at UFC 169, but Fabricio Werdum doesn’t expect to see the best Overeem ever on Feb. 1.

According to Werdum, Overeem hasn’t been the same dominant heavyweight since he failed a pre-fight drug test (elevated testosterone-to-epitestosterone ratio) before his title fight with Junior dos Santos at UFC 146. Overeem has suffered consecutive knockout losses to Antonio "Bigfoot" Silva and Travis Browne since.

"He lacks a little bit in gas because of his steroids," Werdum told MMAFighting.com. "He changes a lot if you take his juice off. Everybody saw what happened. Overeem is one fighter with his juice, but he changes completely without the juice. They took his powers."

Despite the recent losses, Werdum expects Overeem to defeat the former heavyweight champion at UFC 169.

"Let’s see how he does against Frank Mir, if he changed his strategy or training," he said. "Frank Mir is not doing well recently too, but I believe Overeem will defend the takedowns and knock him out. Overeem is a good fighter, but let’s how he does without his juice."

Werdum and Overeem fought twice in MMA. The Brazilian scored a submission victory in Pride back in 2006, but suffered a unanimous decision loss five years later in Strikeforce.

"I don’t like Overeem very much," Werdum said. "Not because of the fact that we fought, but I think he’s too cocky. But he’s a good fighter, a strong guy, a good striker. I respect him for everything he has done in MMA and K-1."