For Velasquez, loss to Dos Santos is past history

• Cain Velasquez was knockout out in the first round by Junior dos Santos in their first fight
• Velasquez was undefeated at the time, but also had an injured knee
• Another loss to Dos Santos could end Velasquez's shot at UFC heavyweight title

But the former Ultimate Fighting Championship heavyweight titleholder admits that it might not have been in his best interest to fight Junior Dos Santos the night of Nov. 12, 2011.

Not that he's acknowledging any regrets. Velasquez has a shot at redemption in the main event of Saturday's UFC 155: Dos Santos vs. Velasquez II (pay-per-view, 10 p.m. ET) at Las Vegas' MGM Grand Garden Arena.

"I don't think it was the best decision," Velasquez said of the first Dos Santos fight. "But I did it anyway, so it's in the past."

At the time, Velasquez was the UFC's undefeated heavyweight champion and riding high after a first-round domination of Brock Lesnar. His first title defense was selected to headline the UFC's first live event on Fox, and a network-televised win was expected to catapult the Mexican-American champion into superstardom.

In the weeks leading up to the event, there was speculation Velasquez had a knee injury. At the time, Velasquez (10-1 mixed martial arts, 8-1 UFC) adamantly denied it, but video recently surfaced that shows the fighter grimacing in pain and clutching his left knee during a pre-event training session. The incident reportedly took place 14 days before the fight with Dos Santos (15-1, 9-0), but Velasquez said he never considered bowing out.

"It was just me being a fighter," Velasquez said.

As it turned out, Dos Santos was also nursing a knee injury — a torn meniscus — that he would have surgically repaired after the fight. Still, when the two entered the cage, the Brazilian slugger landed a vicious overhand right to the temple that sent Velasquez toppling to the canvas. Dos Santos followed with a flurry of nine punches, and referee John McCarthy called the fight after 64 seconds.

"Junior is very quick," Velasquez said. "He has a lot of power in his hands. He timed it perfectly, and it landed."

Velasquez rebounded with an impressive first-round stoppage of Antonio Silva in May.

This time the reward of the UFC heavyweight belt hangs in the balance. But the fight also comes with risk. Historically, an 0-2 mark against a UFC champion means a third shot is highly unlikely.

Future UFC Hall of Famers Rich Franklin and B.J. Penn, for example, were forced to seek work in other weight classes when they dropped two bouts to dominant champs Anderson Silva and Georges St-Pierre, respectively.

A humble, blue-collar fighter with a mean poker face, Velasquez is tough to read when asked if he fears such a scenario.

He insists he hasn't considered any of the periphery possibilities surrounding his fight.

"I'll just go out there and fight my fight, and that's it," Velasquez said.

A two-time All-American wrestler at Arizona State, Velasquez wasn't able to fully use his grappling prowess in the first fight with Dos Santos, who easily thwarted the lone takedown attempt. How much Velasquez's ailing knee played a role is unknown, but it's safe to say he won't want to risk standing in front of Dos Santos longer than necessary.

"I know how he fights," Velasquez said. "He's got good boxing. I've just got to fight my style of fight, which means a lot of pressure and a lot of offense."

UFC 155 marks the first rematch of Velasquez's career, and it could prove a pivotal moment.

A win brings him back to the top of the UFC's heavyweight mountain. A loss could send him spiraling toward irrelevancy in a division that's welcoming more and more talent each month.

But Velasquez isn't thinking about what comes next. For now, it's all about regaining the belt.

"The only reason I got into this sport was to be the champion," Velasquez said. "And now that I'm not champion, it's the only thing that's on my mind right now — to go in there and to win this fight."

John Morgan also writes for mmajunkie.com.