Even for heroes, the end doesn't always come gracefully.

Randy Couture is, and forever will be, a seminal figure in mixed martial arts, even though the era of 'The Natural' is now over. Years after most pro athletes have retired, the 47-year-old Couture was still competing and excelling in a young man's sport, but no more.

His epic run came to a definitive close at UFC 129, his defeat overshadowing everything else at the biggest MMA show in North American history, when a crowd of 55,000 filled the Rogers Centre, as well as Georges St Pierre's sixth consecutive title defence.

It ended with the legend going out on his shield like a true warrior. 

Facing a fighter 15 years his junior, Couture struggled to implement his traditional game plan of closing the range, initiating the clinch and taking his foe to the ground.

Instead, Lyoto Machida used his brilliant footwork to keep him at a distance and capitalised on a clear speed advantage to blitz the former champion with power strikes. Then in the second round, Machida emulated his teammate Anderson Silva, using the same front kick Silva used to knock out Vitor Belfort earlier this year to flatten Couture. Machida finished with strikes from the top before referee Yves Lavigne pulled him off at the 1:05 mark. 

After nearly 14 years of action, 30 fights, five UFC championships and numerous memories, Couture said that it was finally time to hang up his gloves. "No, you're not going to see me again," Couture said shortly after the fight. "This is it." 

As Couture stood in the cage for the final time, the record crowd chanted his name, and the American waved good-bye. He rode off not in a limo, but in an ambulance, sent to hospital for precautionary tests. 

Couture, who retires with a record of 19-11, lost not only his final fight, but also one of his front teeth, knocked out as a result of the kick. Even in defeat, he laughed at his plight, telling UFC commentator Joe Rogan: "I think the last time we had this conversation, I had all my teeth." 

While Couture had been adamant that this was it — win or lose — others had not been quite so sure. Among them was UFC president Dana White, who all week voiced his doubts about it. 

By the end of the night's fights, though, White had changed his mind, admitting it was probably the right time for him to exit the sport.

In the post-fight press conference, White said he hoped fans would recognise Couture's immense contributions in the cage and out.

"Before the pre-fight press conference, I said I don't think we celebrate Randy Couture enough," White said. "Everyone went crazy when George Foreman KO'd Michael Moorer. Randy is 47 and fighting against 20-somethings. He's an amazing human being. To see him end like this ... you know what I was saying before the fight. I think he should retire, too. He went out on a high. He went seven minutes with Machida, and that's still a big deal." 

Couture has retired once before. In February 2006, after being knocked out by Chuck Liddell, he said he would never fight again. More than one year later, he returned and shocked the MMA world by thrashing Tim Sylvia en route to the UFC heavyweight title, a win that made him, at 43 years of age, the oldest champion in UFC history. 

For Couture, it was always about respectful athletic competition, and it was that attitude that helped soften some hard stances towards MMA from its detractors.

For those who didn't understand the sport, it never seemed to make sense how Couture could transform from a gentleman outside the cage to a relentless champion inside it. That ability, along with his amazing story of extended success, was one of the keys to MMA's rise over the last decade. 

He retires with several records, including participating in 15 title matches, and boasting career wins over ex-champions Chuck Liddell, Tim Sylvia, Tito Ortiz, Vitor Belfort, Kevin Randleman, Mark Coleman and Maurice Smith. 

Out of respect, the Rogers Centre crowd stood and applauded the legend. It was Machida's win, and St Pierre's night, but when it comes to a single moment that will be recalled in the years to come, it will be Couture's moment, the night a legend said a sad good-bye.