Antonio Rodrigo Nogueira, one of the greatest heavyweights in mixed martial arts history, announced his retirement Tuesday at a press conference in Rio de Janeiro, exiting the sport at the age of 39.

Nogueira (34-10-1, 1 NC) leaves a career that spanned 17 years and stretched across several different eras of the sport, from its NHB infancy to its place today among the global mainstream.

Along with continuing to captain the successful Team Nogueira fight team, "Big Nog" will move into a professional capacity with UFC in Brazil, aiding social projects and helping to discover new talent for the organization.

"'Big Nog' is a legend in the sport of MMA," said UFC president Dana White. "He is respected by fighters and fans worldwide. It has been an honor to watch him compete and I'm happy to see him retire. He will be a huge asset to the UFC, the athletes and the sport as an ambassador. I look forward to working with him in this new chapter of his life."

"I have mixed feelings," Nogueira said. "I'm sad for leaving but happy with this new job in the UFC. I remember when I met [Junior dos Santos], he was brave in training, and before his UFC debut against the current champion Fabricio Werdum, I told Dana White to watch for his uppercut. And that's how he beat him. I have good eyes for new talent, and I will look for new talents in this new generation."

One of the most respected heavyweight submission artists of all-time, Nogueira began his career at the age of 23 in DeLand, FL, defeating David Dodd at WEF 6 with a first-round kimura. After fighting once more for WEF, the Brazilian took his talents to Japan, where he would eventually gain international stardom over the course of the next decade.

Nogueira debuted on Japanese soil in 1999 fighting in the early Rings: King of Kings one-night tournaments against the likes of Dan Henderson and Valentijn Overeem, before transitioning into Pride Fighting Championships. It was within Pride that Nogueira truly made his name, embarking on an iconic seven-fight win streak that saw him seize the Pride heavyweight title and defeat a litany of big names, from Henderson, Heath Herring, and Mark Coleman, to Bob Sapp, Gary Goodridge, and Semmy Schilt.

Nogueira's run crested into a memorable trilogy against Fedor Emelianenko, of which the Brazilian went 0-2 with one no contest. But losing his title did little to slow Nogueira's reputation as one of the world's greatest heavyweights, as "Big Nog" captured huge victories over Mirko "Cro Cop" Filipovic, Ricco Rodriguez, Sergei Kharitonov, and Josh Barnett before the collapse of Pride led to his move to the UFC.

Though he came to the UFC late in his career, Nogueira still fought 11 times inside the Octagon, most notably winning the interim UFC heavyweight championship with a third-round submission over Tim Sylvia in 2008. Nogueira went on coach The Ultimate Fighter three separate times, while also outpointing Randy Couture, knocking out Brendan Schaub, and submitting Dave Herman, the latter of which proved to be the final win of his career.

Nogueira's time in the sport ended with a three-fight losing streak. His final performance, a unanimous decision loss to Stefan Struve in his native Brazil at UFC 190, prompted White to ask for his retirement.

"I started fighting in 1999, and was at the top 3 of the division until 2008," Nogueira said. "It's an entire life. I have constant pain, fought guys heavier than this 265 pounds limit today. I love the training routine but I have to be 100 percent to fight.

"In my last training camp, I felt I was lacking something, the physical part, and it as a good time to stop. I wish I had come out with a win, but that's not the most important.

"I've always had a passion to follow the development of new athletes and that's what I intend to continue doing," he added. "I want to help further the spread of MMA around the world and give my contribution to the emergence and development of young talent. I appreciate all the confidence that Dana White, Lorenzo Fertitta and Frank Fertitta have in me, and I believe we will reach big results together. I know that I can, and will, contribute much to the growth of our sport outside of the Octagon."