Former champion Anthony Dirrell starts road to redemption vs. Marco Antonio Rubio

Former world champion Anthony Dirrell has spent much of his life dealing with adversity.

We're talking major adversity. Dirrell knocked out his most feared foe, cancer - non-Hodgkins Lymphoma - with a powerful one-two punch of hope and prayer and advanced medical technology, including radiation and chemotherapy, in 2006.

Then, just as his career was taking off after returning from a 20-month hiatus to corral his illness, he was involved in a wicked motorcycle crash, hitting a car that pulled out in front of him. He broke his leg and fractured his wrist and was sidelined for another 18 months. He still has a rod in his left leg from his knee on down. As you might expect, motorcycles are just a bad memory for him.

Now the Flint, Mich., native has one more slice of adversity to cut through: The word "former" in front of world champion.

In the first defense of the WBC super middleweight belt he won against Sakio Bika in 2014, Dirrell lost a tough majority decision and the belt to Swede Badou Jack in April, a decision Dirrell stills believes should have been his. It was doubly tough because it was the first loss of his professional career.

Dirrell (27-1-1, 22 KOs), nicknamed "The Dog," begins his road to redemption Sunday when he takes on veteran Mexican brawler Marco Antonio Rubio (59-7-1, 51 KOs) in a super middleweight showdown at the American Bank Center in Corpus Christi, Texas (PBC on CBS, 4 p.m. ET).

"I'm ready to get back in the ring and prove that I'm still one of the most dangerous men in the game," Dirrell said. "Rubio is a tough guy but I'm coming to knock him out and eventually get my title back. 'The Dog' is coming to Texas looking to inflict some pain."

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Rubio, 35, is one of the most experienced fighters around and has pulled plenty of upsets throughout his 16-year career. None bigger than his knockout against David Lemieux, the Canadian who is fighting Gennady Golovkin for the middleweight title at Madison Square Garden on Oct. 17.

He's also beaten Carlos Baldomir, Jorge Cota and Rigoberto Alvarez while challenging for world titles three times.

"This is a tremendous opportunity for me and I'm going to leave it all in the ring," Rubio said.

Dirrell, 30, whose brother Andre was a bronze medalist in the Athens Olympics and whose career was temporarily derailed following a vicious punch while he was down against Arthur Abraham several years ago, says he would change nothing in his life.

"Everything that happens, happens for a reason. That's what I believe," he said in a recent Q&A on his career. "If you start going back and changing things, you'll never know what it was like to be in the position that you're in."

His biggest achievement in life, he said, to no one's surprise, is beating cancer.

"I think that's the biggest thing anyone can ask for," he said. "If you can get through that, you can get through anything."