It's the return of Cain Velasquez at UFC Fight Night this weekend in Phoenix, as the two-time heavyweight champ will grace the Octagon for the first time since July 2016.

Standing across the cage will be former title challenger and all-around scary dude Francis Ngannou, who is looking to book another shot at a heavyweight championship. He came up short in his first title bid in January 2018.

It's a big heavyweight fight, with big implications for the division. Here's everything you need to know.

Cain Velasquez (14-2) vs. Francis Ngannou (12-3), heavyweight

Odds: Velasquez -160; Ngannou +140

Francis Ngannou first brought up the possibility of a fight against Cain Velasquez in January 2017.

Ngannou had just knocked out former champion Andrei Arlovski in the first round of a non-title bout, and even though the French-Cameroonian slugger was just three years into his professional career, no one batted an eye at the thought of him squaring off with Velasquez. His rise was that impressive.

Of course, the fight didn't happen in 2017. Velasquez underwent back surgery that same month Ngannou mentioned his name, and has been sidelined until now.

Ngannou's original callout of Velasquez was based on nothing but respect. When the now-32-year-old heavyweight was first introduced to MMA in 2012, Velasquez was at the peak of his career -- reclaiming the UFC championship for the second time.

"When I heard about MMA, I went on YouTube and started to watch MMA heavyweights," Ngannou said. "I watched the champ, Cain. I watched Alistair Overeem, Junior dos Santos, Brock Lesnar. Cain was a great fighter for someone who didn't know the sport. I was very impressed.

"I said, 'At some point, I have to fight these guys. If you beat them, that means you are great. To be the best, you have to beat the best.'"

Francis Ngannou is coming off a first-round TKO win against Curtis Blaydes in November. Jeff Bottari/Zuffa LLC via Getty Images

That respect is now mutual between Ngannou and Velasquez. Even though Ngannou suffered two high-profile losses in 2018, he ended the year with a 45-second knockout of Curtis Blaydes -- and Velasquez's coach, Javier Mendez, believes he is the toughest fight in the division outside of Daniel Cormier, who is Velasquez's teammate.

"For me, the Francis Ngannou fight is not the fight I wanted," Mendez admitted. "That's the toughest guy in the division for us stylistically, because he has the one thing you cannot take away from him. Power. And he's got his mojo back.

"We're getting the toughest Ngannou ever. Outside of DC, there's no other guy who is tougher for us. But that's the next step."

Fight breakdown

ESPN Stats and Information

Heavyweight MMA is always tough to predict. Throw in the different variables surrounding these two, and this fight is nearly impossible to read.

Velasquez hasn't fought in 2½ years. During that time off, he dealt with a serious back injury. That's a lot to come back from, especially at 36 years old.

As for Ngannou, his five-round loss to Stipe Miocic one year ago exposed some holes -- and there's really no way of knowing for sure whether those gaps have been closed. There was virtually nothing to learn from his awkward, throwaway fight against Derrick Lewis in July, or his 45-second knockout of Blaydes in November.

On paper, Velasquez has the advantage. He's capable of using the same game plan used by Miocic, and (assuming he's healthy) can probably implement it better. Ngannou was lost on the ground against Miocic, and his energy level cratered by the second round. Velasquez pushes an even harder pace, and his control from top position is terrific.

One positive sign from Ngannou is that he noticeably trimmed down following the Miocic loss. He weighed in for that title fight at 263 pounds. In the two fights since, he's weighed 254 and 253. A trimmer Ngannou is a scarier Ngannou to me, as it should naturally translate to better speed and cardio.

The obvious knock on Ngannou targets his wrestling, but I don't think it's fair to say he's easy to take down. He's a strong, athletic heavyweight who moves very well. But in that loss to Miocic, the effort of denying a takedown gassed him out so badly, all of his defense suffered -- grappling and striking.

Look, Ngannou doesn't need to stay on his feet long. He needs one punch to put Velasquez out. That will be easier said than done, though, given the way Velasquez moves his head, will put Ngannou on his back foot and force him to respect the takedown. If Ngannou can stop Velasquez from sustaining that early momentum, however, or if Velasquez isn't what he used to be, we could definitely see a Ngannou win.

Prediction: Velasquez via TKO, second round.