Referee Mario Yamasaki gave Lesnar every chance to recover, but after he did little but cover up, the bout was halted at the 2:26 mark of the opening round.
"Today was all about bad intentions," said Overeem, who promised to do the same to the current champ. "It was a nice K-1 body kick.
"Junior Dos Santos is next. I promise you guys that."
After the fight, an emotional Lesnar addressed the crowd and addressed the speculation.
"I've had a really difficult couple years with my disease," said Lesnar. "And I'm officially going to say this is the last time you'll see me in the octagon."
Here is a recap from our UFC 141 report: Referee Mario Yamasaki is the third man in the cage for tonight’s scheduled five-round main event and heavyweight title eliminator. Lesnar bounces on his toes to begin as Overeem crouches and approaches with caution. Lesnar wades inside and ducks under an overhand right. Overeem hops away from a Lesnar single leg but he’s cut above his right eye. Stepping in, Overeem lands a solid knee to the body, then shoves him into the fence. More knees up the gut land on Lesnar and the ex-UFC champ is composed but moving backward. Lesnar is throwing single left crosses and gets jacked with another big knee. A kick to the liver sends Lesnar to the floor, covering up. Overeem stands over his crouching, covering opponent, socking Lesnar with heavy right hands until ref Yamasaki steps in. The TKO finish comes officially at 2:26 of round one.