Mikey Garcia, the reigning WBC lightweight champion who is 39-0 with 30 knockouts, is moving up two weight classes to take on IBF welterweight champion Errol Spence, at 24-0 with 21 knockouts.

Spence is defending his title in the 147-pound division for the third time. He stopped previously undefeated challenger Carlos Ocampo with a first-round knockout at the Dallas Cowboys' practice facility in Frisco last June, not far from his home in Desoto.

This title defense is a pay-per-view match from AT&T Stadium, where the Cowboys play their home games and where the ring will be centered under the looming 72-foot tall video boards that stretch between the 20-yard lines.

Garcia grew up around Oxnard, California, where the Cowboys hold part of their preseason training camp each year.

Not only is Spence used to the heavier division, the 29-year-old southpaw is about three inches taller and has a longer reach. But he doesn't think the size difference is what gives him the advantage.

While acknowledging that "on paper" Garcia is his toughest opponent to date, Spence said he won't know for sure until they get into the ring. And Spence feels like he gets something significant with a victory, other than just retaining his title.

The 31-year-old Garcia, whose current title is in the 135-pound division, had sparring partners 20 pounds heavier than him during training for the rare double-division jump.

Mikey Garcia knows he has to fight the best fight of his life, and insists that people haven't yet seen the best of him in the ring because he hasn't yet had an opponent like Spence.

Spence views this fight as the necessary step to enter the superstar leagues of the sport - just like Floyd Mayweather.

"I feel like Floyd [Mayweather] opened the door and I'm gonna kick it down," Spence said to TMZ.

"I feel Im the guy that's next up to be the superstar and icon in the sport of boxing."