ANAHEIM, Calif. » In just his seventh mixed martial arts fight, Brock Lesnar is carrying an awful lot of pressure on his shoulders. Fortunately for the UFC, its hulking heavyweight champion is certainly built for the task.

The former pro wrestler who has improbably evolved into the UFC’s biggest star faces the toughest challenge for his belt to date at UFC 121 tonight at Anaheim’s Honda Center. Cain Velasquez is younger, more experienced in MMA and unbeaten during his relentless rise to the top of the UFC heap.

Lesnar (5-1) was sent straight to the top thanks to his wrestling fame, yet he has earned the entire league’s respect since then with his training regimen and remarkable improvements over the past three years. After losing a year of his career to a medical problem, Lesnar is fighting for the second time in less than four months — and he’s grateful for every ounce of pressure, every bit of danger.

"At the end of the day, I love this," Lesnar said. "I don’t have to prod myself out of the bed in the morning. I try to be the first one in the gym. I’m so thankful and glad there’s a UFC. If there wasn’t, I don’t know what I’d do with myself."