1. Robbie Lawler vs. Rory MacDonald 2 | UFC 189
There have been a number of back-and-forth wars on this list. However, the ultimate example of such an all-out war was the rematch between Lawler and MacDonald for the welterweight crown in 2015, which takes the top spot. Lawler had become the new welterweight champion a fight earlier thanks to a highly controversial split decision over Johny Hendricks. MacDonald had distinguished himself as the best welterweight in the UFC aside from those two men, looking incredible in winning three straight since a split decision loss to Robbie Lawler in 2013, a streak that included lopsided decisions over Demian Maia, future champion Tyron Woodley, and a knockout of the now sadly forgotten contender Tarec Saffiedine. In fact, the 25-year-old MacDonald was actually a moderate favorite for this contest! What ensued was an insane 21-minute bloodbath with more concussive blows taken by both men than 5 knockouts put together! The claim that a fight takes years off a fighter's career is overused and typically an exaggeration, but it applies here. Neither Lawler nor MacDonald were the same after the fight, both suffering at least a small reduction in their speed and reaction times afterwards, a common result of heavy head trauma. MacDonald also suffered a gruesome broken nose that required surgery to fix and would haunt him throughout the rest of his career, being continuously broken and requiring further surgeries. Both men left a part of themselves in the cage that night to put on a scintillating, timeless war for the fans. Nor did it lack for drama and huge shifts in the battle. Lawler started great, clearly winning Round 2 and most of Round 3, breaking MacDonald's nose and leaving his face a mask of blood. Out of nowhere, MacDonald nailed Lawler with a head kick late in Round 3 and very nearly knocked him out with follow-up punches and head kicks. Only seconds into Round 4, MacDonald hammered Lawler with another head kick and proceeded to batter him from pillar to post early in the stanza, though the champion recovered and began landing hard shots of his own.
At the end of the round, they had an iconic staredown with Lawler spitting blood on the canvas, each of their faces a gruesome, misshapen, bloody mess, looking like a victim in a slasher film. In the final minute, Lawler landed several hard punches, though it was a relatively innocent straight left that landed right on MacDonald's obliterated nose that caused the challenger to sink to his knees, with Lawler dutifully pounding him out to retain his throne. While those were the memorable rounds, I would like to point out that the opening frame was a relatively cautious affair, with both men feeling one another out and getting a sense for the distance. One can even hear a few boos at one point! If that's not a lesson to reserve judgment on a fight until it's over, I don't know what is. When it comes to high drama, toe-to-toe bloodbaths, and incredible toughness and heart with a title on the line, nothing can compare with this classic.