Mirko (Cro Cop) Filipovic says it was his head more than anything else that led to his struggles in his first run with the UFC.

The Croation heavyweight spoke on a conference call ahead of his fight Saturday in Cologne, Germany against England's Mostapha Al Turk, which will mark his return to North America's premier promotion after nearly a two-year absence. Filipovic (24-6-2, 1 NC) tried to answer why he didn't have the same success transitioning from the ring in Japan to the UFC's Octagon.

"I just think I wasn't the old Mirko Cro Cop I used to be," he said. "I don't know the reason. Maybe I was just empty after winning the Pride Grand Prix. Maybe I didn't adapt to the cage. Maybe I wasn't hungry enough, maybe I didn't smell the blood like I did in my previous fights.

"It was a problem with my head, nothing to do with my body."

The former Pride star, who won his UFC debut but then lost two straight to Gabriel Gonzaga and Cheick Kongo in September 2007 before returning to fight in Japan, believes he has a renewed focus and a better mental approach this time around.

"I had surgery in January and had a lot of time to think, and decided to return. And I think my conditioning is better than ever," the 34-year-old added. "I just want to return to the top. I just want to prove my worth."

UFC president Dana White, who was also on the call, said he believed the hunger Filipovic displays is genuine and will be evident when he returns to the cage at UFC 99.

"When Mirko and I talked on the phone the day he said he wanted to come back, he was all fired up, he wanted to take a run at the title," said White, who added he's spoken to a lot of different fighters and can tell when one means business.

Cro Cop, who has his own cage in the training room in his house in Zagreb, Croatia, has been working extensively in it and believes he is better prepared for the differences it presents from fighting in the ring where he first established himself as a mixed martial arts superstar.

"I underestimated the cage," Filipovic admitted. "It's much easier to go from cage to the ring than from the ring to the cage.

"Many experienced fighters like to use the cage. It's not so easy when somebody puts you on the wire, you cannot move. In the ring, you just have to put your head outside the ropes and the ref will stop the fight and put you back in the middle. It's a lot easier to escape."

The way Saturday's UFC 99 bout against Al Turk, who was originally scheduled to take on newcomer Todd Duffee, came together was unprecedented. White, who called his relationship with Filipovic a great one, said the two spoke one Sunday and the whole deal, which is just for the one bout, was done verbally over the phone.

"In the history of the company I've never done this with anybody ever," White said.

Filipovic, who had gotten offers to fight in other promotions, said he accepted this one without even knowing anything about his opponent. He just knew it was time to return.

"I owe a lot to the UFC and UFC fans," Filipovic insisted.