It's a shot at history for Miocic, as he tries to become the first heavyweight titleholder to ever defend the belt three consecutive times. And he'll do so against Ngannou, one of the fastest-rising title challengers in recent memory.
In the co-main event, Daniel Cormier faces first-time title challenger Volkan Oezdemir. It's the first light heavyweight title fight since Jon Jones was stripped of his belt for the third time -- in this case, due to a failed drug test. More on that fight here.
Stipe Miocic (17-2) vs. Francis Ngannou (11-1), heavyweight championship
Odds: Ngannou -180; Miocic +160
An "underdog champion" meets the UFC's "shiny new toy."
Shortly after making a successful title defense against Junior dos Santos in May, Stipe Miocic addressed the media at a postfight press conference.
Despite a brilliant first-round knockout that night, Miocic's demeanor was not overly joyful. When asked about his immediate plans, Miocic sternly responded, "There are a lot of things that need looking into. Let's leave it at that."
It was no secret Miocic, 35, was talking about his UFC contract.
In late 2016, Miocic defended the title against Alistair Overeem at UFC 203, in his hometown of Cleveland. Per commission records, Miocic's purse was $200,000 less than Overeem's for that event, even though Miocic held the role of champion. He said later he wanted that situation rectified.
Since accepting the Ngannou fight, Miocic has been noncommittal regarding the outcome of any contract renegotiation. He recently told ESPN he feels disrespected, but added, "I'm here to fight and that's all I care about."
Ngannou, meanwhile, appears to have the UFC's full support. He moved to Las Vegas last year and trains at the promotion's Performance Institute, which is connected to its headquarters.
President Dana White has referred to him as "the next big thing," and it's easy to see why. His vicious knockout against Overeem last month was one of 2017's best. He's finished his previous four opponents inside the first round, and his backstory as a poor Cameroonian-Frenchman is extremely compelling.
Miocic has openly said he believes the UFC wants Ngannou to win, but has promised nothing will change in Boston.
"He's a shiny new toy to them -- that's pretty much what it is," Miocic said. "[The feeling of disrespect] has gotten more and more worse.
"Listen, the guy has hype behind him and he should, he hits hard. I see these things about how he's going to change the division. That's fine, he can change it after I'm done."
Francis Ngannou hits hard.
That seems to be the prevailing breakdown of this fight. There's still much we don't know about Ngannou, but those questions mean nothing because ... Have you seen the dude punch?
And heck, there might be a lot of truth to that. Maybe Ngannou's power has masked some deficiencies. If that's the case, the question is: Can Stipe Miocic survive long enough to show them?
Miocic poses several challenges we haven't seen Ngannou deal with before. Wrestling is a big one. Miocic is a former NCAA Division I national qualifier wrestler, with the endurance to keep it up over 25 minutes. That's not something Ngannou has faced yet.
Miocic is also very good at backing opponents to the fence and cornering them there. Ngannou hasn't spent a ton of time in that position. How he may handle extended periods of time there is worth wondering about, especially the longer a fight goes.
And that last point is potentially a big one in this five-rounder. There is prior evidence Ngannou slows down over time. It makes sense, considering his size and haymaker style of punches. Stamina is a key area Ngannou has focused on since moving to Las Vegas.
If Miocic can get into an early rhythm with his jab, walk Ngannou to the outside and fit in a takedown here and there, the endurance of Ngannou is something to monitor. Yes, he hits like a truck, but if the speed tapers off, he'll at least be a manageable foe on the feet.
Miocic has far more experience under these circumstances. He's gone five rounds with dos Santos and has headlined six UFC events. He's knocked out Fabricio Werdum in a Brazilian soccer stadium. At this point, it's reasonable to believe that experience, plus his style, gives him an edge late.
But Miocic's pressure leaves him vulnerable. He's taken his share of damage and been dropped in the first round before. One mistake could cost him everything here.
Prediction: Miocic via TKO, third round.