Rivalries, the worthwhile ones at least, are compelling because they force the relevant parties to conjure the greatest version of themselves.
At UFC 202 in Las Vegas' T-Mobile Arena, the world saw Conor McGregor as never before. In defeating the preternaturally robust Nate Diaz via majority decision in their eagerly anticipated rematch, the Dubliner emptied the entirety of his being onto the blood-soaked canvas.
Over the course of the 25 brutalising minutes, McGregor and his grisly foe bludgeoned each other with ferocious abandon. Yet, this was no backroom brawl, the exchanges were unquestionably crude at times, but the technique was not once diluted.
McGregor executed the game plan those few who backed him knew was his only legitimate path to victory and, indeed, vengeance.
The headhunting he employed so redundantly in the first bout at UFC 196 was largely disposed of and, instead, McGregor diversified his output.
In the early goings, he peppered Diaz's front leg with thumping kicks and scored regularly with left hands to the midriff and skull. One such haymaker floored the Californian but McGregor remained patient instead of recklessly pursuing the finish.
Twice in the second stanza McGregor dropped Diaz with clubbing shots but, as is his wont, the latter rallied and began to apply pressure.
The third proved a purple patch for Diaz, who found joy from the clinch and roughed up McGregor close in. It felt like the tide was turning.
As McGregor entered the first fourth round of his career, he wrested back the momentum, just when it was entirely conceivable that he might wilt under the strikingly bigger American.
Diaz is renowned for improving as fights mature and it was thought he may dispatch of the Crumlin man in the 'Championship rounds'.
Indeed, he had the better of the fifth frame and, subsequently, when the final buzzer sounded, discerning the victor was nigh on impossible.
Two of the judges scored it for McGregor, while the third deemed this instant classic a draw.
However, all things being equal, one could not gripe with the decision, though many tried.
McGregor earned an unprecedented $3m purse for his efforts, though that figure is expected to rise to $10m when his cut of the pay-per-view buys is tallied.
Moreover, he gained his revenge and, more significantly, an indisputable validation for navigating the greatest obstacle he's ever encountered. No more can anyone legitimately dismiss him as some belligerent Trojan horse.
Immediately after the bout, which reduced McGregor to hobbling on crutches, talk of a trilogy fight was rampant.
Perhaps down the line, but certainly not next. This victory gives McGregor options and leverage so, regardless of what his employers might say in public, he once again holds all the cards.
He may rematch Jose Aldo, who now holds the interim featherweight title or, more appealingly, McGregor could agitate for a crack at lightweight champion Eddie Alvarez.
That was the plan before Diaz strangled him into submission, to be the first fighter ever to concurrently hold two titles.
Interesting times lay ahead in the world of Conor McGregor.