LAS VEGAS — Brock Lesnar was everything he was purported to be in his UFC debut.

Unfortunately for the former WWE star, Frank Mir was, too. Mir, the ex-UFC heavyweight champ whose career was nearly derailed by a 2004 motorcyle accident, survived an early pounding to submit Lesnar at 1:30 of the first round Saturday at the Mandalay Bay Events Center.

Lesnar, a college wrestling national champion, easily took Mir down twice in the early going and was pounding away with fists and elbows to the grounded Mir. But Mir worked for submissions and eventually worked into a knee bar that forced Lesnar to tap out.

Mir had failed twice to get an arm bar on Lesnar, whose massive arms made it difficult.

"His legs were leaner, so I went for those," Mir said.

Lesnar took Mir down only 10 seconds into the fight and it looked for a second as if the bout might end early. Lesnar was in Mir's guard and pounding away, but punched Mir in the back of the head, a foul that cost him a point.

As soon as the bout resumed, Lesnar took him down again and began to repeat the pummeling.

"It feels spectacular, because I had Brock Lesnar dropping elbows on my head and I still pulled through that and got a submission," Mir said.

The end came as Mir failed to get an arm bar on Lesnar. Lesnar tried to move away and Mir snatched his ankle and quickly slapped on the knee bar. Lesnar had to tap very quickly.

In only his second mixed martial arts bout, Lesnar took on the challenge of one of the top fighters in the world. He said he would continue to fight.

"I came out trying to pressure Frank (because) I questioned his heart," Lesnar said. "I was just trying to get a bunch of shots in there and I left my leg out there. He's a top-notch jiu-jitsu guy and he got me tonight. He's the better fighter."