A day before the UFC is set to announce its historic return to Brazil, a major cornerstone of their history announced his retirement on Twitter...kinda.

At around 8:30 pm EST, UFC Hall-of-Famer Randy Couture posted the following on his Twitter page:

"Thanks to everybody who's been tweeting about seeing my fights I must have missed the memo :) I think I'm at the end of it Yall . It's time."

Note the "I think". There has been no formal announcement by the UFC or Couture, but seemingly that is as official as it's going to get for now.

Couture has been hinting at retirement for months as his film work has increased with two movies either currently in production or set to start in early 2011.

The 47-year-old began his professional MMA career in May 1997 at UFC 13. Still under the one-night tourney format, Couture won the heavyweight tournament that night with two victories. Later that year, he won the UFC Heavyweight Championship after defeating Maurice Smith via majority decision at UFC Ultimate Japan.

He later left the organization in a contract dispute and didn't return until November 2000 when he defeated Kevin Randleman via 3rd round TKO to win his second UFC Heavyweight Championship.

Couture defended the title twice before losing to Josh Barnett, who later tested positive for steroids. After losing to Ricco Rodriguez to fill the vacancy, Couture moved down to light heavyweight and began an epic trilogy with Chuck Liddell that helped the two on the path to mega-stardom.

He held the 205-pound title twice (three times if you count interim gold) and last competed for the title in the third Liddell fight at UFC 57 in February 2006. He lost that night and returned to heavyweight, beginning an incredible run that endeared him to the then-growing MMA community.

Couture returned to the Octagon in March 2007 to battle then-Heavyweight Champion Tim Sylvia. Couture worked over Sylvia for five rounds and took a unanimous decision win to earn back the championship. After defending the belt against Gabriel Gonzaga, Couture and the UFC were at odds again over money. This kicked off a year of litigation, a much-discussed dream fight with Fedor Emelianenko and lots of bad blood.

But money and time heals all wounds and Couture returned to the UFC in the fall of 2008, still as the organization's champion. His first fight back? UFC 91 against Brock Lesnar, a battle that Lesnar won via 2nd round TKO to take the title. It was Couture's last fight for a championship.

Since then, Couture fought a classic against Antonio Nogueira (loss) and then ripped off three wins in a row over Brandon Vera, Mark Coleman and boxer James Toney, the latter coming at UFC 118 in Boston, MA, this past August.

It will remain to be seen whether this retirement sticks, but if so, it's been a hell of a ride for "The Natural". I'm sure we'll be seeing plenty of him around for years to come— just in a line of work that doesn't involve getting punched in the face.

Josh Nason is a New England-based freelance MMA journalist that covers live events, has written for FIGHT! Magazine and frequently does radio/podcast appearances. He asks for your "like" for ESPN Boston to cover MMA. Follow him on Twitter.