Former UFC welterweight champion and middleweight title holder Georges St-Pierre officially retired from mixed martial arts on Thursday.
He is one of only six UFC fighters to have held titles in multiple weight classes having also been welterweight champion for 2,204 days and won 26 of his 28 fights from 2002-17.
But what kind of legacy does the 37-year-old Canadian leave?
Here are five reasons he should be considered MMA's greatest of all time.
Throughout the 28 fights of his MMA career, St-Pierre displayed the heart of a true champion with his ability to not only go to the proverbial well to get the victory, but also by beating rivals at their own game.
He out-grappled Matt Hughes, Matt Serra and Jon Fitch, just like he out-struck Josh Koscheck, BJ Penn and Nick Diaz.
He went to war with Carlos Condit and Johnny Hendricks, and conclusively avenged the two losses he suffered inside the octagon.
Between 2007 and 2013 he dominated his weight class, defeating every leading welterweight contender the world could offer.
Even four years away from competition couldn't stop him from weathering a storm to choke out Michael Bisping in November 2017 and add a second weight-class world title to his incredible legacy.
A true martial artist
St-Pierre dedicated his life to martial arts and reaped the rewards.
In a sport, prior to GSP, littered with tough-talking street-fighting men, and more recently, with athletes as focused on the celebrity and entertainment aspect of prize-fighting as they are on training, St-Pierre bucked the trend.
He was always a true professional. Respectful, strategic and athletic, his behaviour was more reminiscent of the characters in the Bruce Lee or Jean-Claude Van Damme movies he adored than that of an overly aggressive, cauliflower-eared, toothless warrior.
Throughout his career, St-Pierre also searched out the best possible coaching to further his lifetime of marital arts education.
His journey took him to Renzo Gracie's in New York, Greg Jackson's in New Mexico, onto the mats with Muay Thai master Phil Nurse, the boxing ring with iconic coach Freddie Roach and, of course, he forged a long-time partnership with head coach Firas Zahabi.
He was always ahead of the curve, too, employing a sports psychologist early on in his title reign to stay on top.
A national hero
When Bisping retired last year, where was the reaction and tribute from British prime minister Theresa May? Likely she has never heard of MMA, the UFC or 'The Count'.
In Canada, however, GSP's career achievements enthralled the nation.
He was voted Canadian Athlete of the Year three times in a row between 2008-2010, and when he announced to the world he was walking away from the sport, Prime Minister Justin Trudeau was one of the first dignitaries to take to social media to offer his admiration.
When he fought Jake Shields in April 2011, GSP proved he also didn't necessarily need the right dance partner to sell tickets, when 55,724 fans (the second biggest gate in UFC history) packed into the Rogers Centre in Toronto in to watch their hero retain his belt.
He makes his own rules
Long before Conor McGregor became the breakout superstar he is, there was another pay-per-view champion in the UFC who wasn't afraid to push back at the top brass.
When you get to the big show, most fighters are all about the three letters - UFC. But St-Pierre had three of his own that were always given priority - GSP. Once he was established as champion, he only took fights when he was ready.
He knew his worth, would push back on contract deals and danced by his own tune. He never swerved anybody, but he never took fights that weren't for the benefit of his own brand either.
He returned last year, beat Bisping and walked away from the 185lb belt. His terms. And that is part of the reason he quit for good this week.
He would have liked to face lightweight champion Khabib Nurmagomedov, the unbeaten Russian who rag-dolled McGregor back in October. But having St-Pierre end the unbeaten reign of a fighter starting out on his PPV journey didn't appeal to the UFC.
After all, St-Pierre would only of likely stuck around for a Conor superfight in victory. Again, always on St-Pierre's terms.
He kept it clean
Long before the UFC partnered up with the US Anti-Doping Agency and employed Jeff Novitzky in a defiant move to clean up MMA, St-Pierre campaigned long and hard for a cleaner sport.
He even walked away from the octagon at one stage in protest at the lack of testing. And while that may not, on the face of it, seem relative to his GOAT potential, his legacy is untarnished. The same cannot be said of his two most decorated rivals.
Anderson Silva, a long-time potential crossover opponent for GSP, and the incredibly gifted Jon 'Bones' Jones both have comparable skill-sets, dominant title reigns and a similar long list of acclaimed opponents inside the octagon.
Yet both of their careers are now stained with multiple drug test failures. St-Pierre has never failed a test. He has never cheated, cut corners or broken the martial arts code of conduct.
And perhaps that above all else is what separates 'Rush' from the best of the rest.