Champion vs. champion fights are a rare event in the UFC, but Saturday sees an epic unification showdown between Khabib Nurmagomedov and Justin Gaethje.
Ahead of UFC 254, we have ranked every UFC unification bout since 2003 - rating them based on excitement and buzz surrounding the event, as well as the manner of the victory.
10 - UFC 44: Tito Ortiz (c) vs. Randy Couture (ic)
Ortiz entered this UFC light-heavyweight unification brimming with confidence after dismantling Ken Shamrock, but he was dominated by Randy Couture who controlled the younger fighter from bell to bell.
9 - UFC 188: Cain Velasquez (c) vs. Fabricio Werdum (ic)
Werdum spoiled Velasquez's highly-anticipated comeback in a back-and-forth affair with the Brazilian submitting the Mexican-American in the third round.
8 - UFC 212: Jose Aldo (c) vs. Max Holloway (ic)
Holloway staked his clam at GOAT UFC featherweight status when he ruthlessly stopped Aldo to become the undisputed champion.
7 - UFC 154: Georges St-Pierre (c) vs. Carlos Condit (ic)
St-Pierre was nearly on the wrong end of another huge upset when Carlos Condit rocked him with a head kick, stunning everyone inside the Bell Centre.
But GSP fought off Condit's onslaught and ground out the victory in one of his best performances ever.
6 - UFC 83: Matt Serra (c) vs. Georges St-Pierre (ic) II
Serra and St-Pierre rematched after 'The Terror' caused the biggest upset in UFC history.
He stopped GSP to dethrone the Canadian megastar from his UFC welterweight crown, but 'Rush' wasted no time in their second meeting as he quickly took care of the American at UFC 83.
5 - UFC 242: Khabib Nurmagomedov (c) vs. Dustin Poirier (ic)
Nurmagomedov endured some difficult patches in his fight against Poirier who had him hurt in the second round after clipping him on the chin.
'The Diamond' had the Russian on the retreat and nearly sunk in a guillotine in the third round. But 'The Eagle' quickly turned the tables and produced his own submission, forcing the tap in a wild sequence.
4 - UFC 116: Brock Lesnar (c) vs. Shane Carwin (ic)
The monstrous heavyweight clash between Lesnar and Carwin saw the interim champion put it on the UFC heavyweight king.
Carwin dazed Lesnar then pounced on him but he couldn't secure the finish, which proved costly as the defending champion fought back to submit the challenger. Still one of the greatest comebacks in UFC history.
3 - UFC 243: Robert Whittaker (c) vs. Israel Adesanya (ic)
An all-Oceanic clash between Whittaker and Adesanya was the last unification in the UFC with the New Zealander putting his Australian counterpart away in the second round in front of a UFC record 57,127 fans in Melbourne.
Adesanya produced a memorable walkout before becoming the undisputed UFC middleweight champion in breathtaking fashion.
2 - UFC 100: Brock Lesnar (c) vs. Frank Mir (ic) II
Lesnar exacted revenge on Mir with a brutal display of ground and pound.
He rained down punches with his lunch-box hands, making Mir a bloody mess on the promotion's biggest night.
1 - UFC 194: Jose Aldo (c) vs. Conor McGregor (ic)
McGregor fulfilled his prophecy in the most dramatic way possible as he ended his rivalry with Aldo by sleeping the dominant champion in just 13 seconds with a precise left hook that immediately knocked him out.
An incredible introduction to the McGregor era.
Featured Image Credit: Sports Net/AP/Esther Lin/Sherdog
Topics: Khabib Nurmagomedov, Conor Mcgregor, Justin Gaethje, UFC News, Fight News, UFC, Israel Adesanya, Brock Lesnar, Georges St-Pierre