#2. Nick Diaz vs. BJ Penn – UFC 137

After his win over Gleison Tibau at UFC 65 in November 2006, Nick Diaz departed the UFC for new pastures.
After fighting for PRIDE, Elite XC and DREAM, he eventually settled into the Strikeforce promotion. While there, he won six fights in a row and claimed the welterweight title with a win over Marius Zaromskis.
Get the latest updates on One Championship Rankings at Sportskeeda and more
In the process, Nick Diaz became one of the biggest stars to be competing outside the UFC. When the UFC bought out Strikeforce in 2011, the clamor immediately began for him to return to the octagon to fight UFC welterweight kingpin Georges St-Pierre.
The UFC obliged and duly matched Diaz with GSP at UFC 137, only to pull the rug from under the Stockton native when he refused to complete his media obligations for the event. Instead, the title shot went to Carlos Condit. Diaz, meanwhile, was given a wickedly tough alternative opponent, former UFC welterweight and lightweight champion BJ Penn.
Like many of Strikeforce’s fighters at the time, Nick Diaz had plenty of doubters. Those doubters all figured that Penn would outclass him. At UFC 137, Diaz proved them wrong in style.
His pressure-boxing game allowed him to drag Penn into deeper waters than many fighters had ever done before. And faced with such a relentless foe, ‘The Prodigy’ was simply forced to drown.
In the end, Diaz beat Penn down to the point that the Hawaiian swiftly announced his retirement from MMA after the fight. A decade later, the win arguably remains Diaz’s most impressive inside the octagon.
#1. Nick Diaz vs. Georges St-Pierre – UFC 158

It almost sums up Nick Diaz’s fighting career as a whole that his most memorable moment in the octagon didn’t come in victory, it actually came in defeat.
The nature of his clash with Georges St-Pierre at UFC 158, a classic tale of good vs. bad that practically transcended the sport of MMA, was always going to make for a great show. But few could’ve predicted that the event would draw more than a million pay-per-view buys, making it one of the highest sellers in UFC history.
The feud between the two welterweights had been more than a year in the making, with Diaz’s callouts of St-Pierre dating back to his career in Strikeforce. After Diaz beat BJ Penn at UFC 137, it looked like the fight would finally happen. But fate intervened in the form of a severe knee injury to GSP, forcing the UFC to delay the fight for more than a year.
That didn’t matter to the level of hype. Diaz directed an insane amount of trash talk at his Canadian opponent, while the usually mild-mannered GSP spoke of Diaz forcing him into a “dark place” in his mind.
And with UFC 158 being booked to take place in St-Pierre’s hometown of Montreal, Diaz embraced the role of villain even more, showing disdain for the Canadian fans even as they wildly booed him.
The fight itself turned out to be less entertaining than some had hoped, as St-Pierre ended up winning in largely one-sided fashion. But in the end, seeing the villainous Diaz lose was essentially what fans were paying for anyway.
And as always with Nick Diaz, somehow, despite the loss and his baseless accusations of St-Pierre using performance enhancing drugs, he came away from the event looking like an even bigger star than before.