What is arguably the most significant fight in UFC heavyweight history is now official.

Champion Stipe Miocic and challenger Daniel Cormier weighed in successfully Friday morning in Las Vegas. Miocic made weight at 233 pounds; Cormier was 236.

Miocic will defend the title against Cormier on Saturday night in the main event of UFC 252. The bout will decide the trilogy between the two men -- Cormier knocked Miocic out to win the title in 2018, and Miocic returned the favor last summer to regain the belt.

Cormier has said this will be his final bout.

Coming in, ESPN has Miocic as the No. 4 pound-for-pound MMA fighter in the world; Cormier is No. 6. At heavyweight, Miocic is No. 1 and Cormier is No. 2.

UFC president Dana White has said that the bout will decide the greatest heavyweight fighter in MMA history.

Ahead of the first fight, Miocic weighed 242.5 pounds and Cormier was 246. At weigh-ins before the second fight, Miocic was 230.5 pounds and Cormier hit the scale at 236.5. The heavyweight maximum for title fights is 265 pounds.

Both men have legendary résumés and are future UFC Hall of Famers.

Miocic (19-3) is a two-time champion and owns the most UFC heavyweight title defenses in history (3). The Ohio native has won seven of his past eight bouts, with the only defeat coming to Cormier at UFC 226 in July 2018. Miocic, 37, first won the UFC heavyweight title by knocking out Fabricio Werdum in May 2016.

When he defeated Miocic two years ago, Cormier (22-2, 1 NC) became only the second UFC fighter to hold two titles in two different weight classes simultaneously. The Louisiana native, who lives and trains in California, was the UFC's light heavyweight champion from 2015 to 2018. He was also the only man to defend one of those titles while holding both.

Cormier, 41, has lost to just two opponents in his MMA career: Miocic and longtime pound-for-pound king Jon Jones.

Both co-main event competitors at UFC 252 also successfully made weight Friday morning for their bantamweight clash. Undefeated prospect Sean O'Malley and Marlon Vera each tipped the scale at 136 pounds.