Antonio Rodrigo Nogueira retires after 16-year MMA career

Antonio Rodrigo Nogueira announced his retirement from professional mixed martial arts Tuesday, bringing to a close one of the most accomplished careers in the sport's history.

Nogueira (34-10-1), who made his debut in June 1999, retires as a former PRIDE heavyweight champion and UFC interim champion. The UFC, where Nogueira has fought exclusively since 2007, immediately announced it would bring Nogueira onboard as an athlete relations ambassador in Brazil.

"It's a great pleasure and an honor for me to further my ties with the UFC," Nogueira said. "I've always had a passion to follow the development of new athletes, and that's what I intend to continue doing. I want to help further the spread of MMA around the world and give my contribution to the emergence and development of young talent."

Nogueira, 39, rose to prominence fighting under the Pride banner in Japan. He became the inaugural Pride heavyweight champion in 2001, defeating Heath Herring via unanimous decision at Pride 17. He went on to defeat the likes of Dan Henderson, Mirko 'Cro Cop' Filipovic, Fabricio Werdum and Josh Barnett.

He is perhaps best known for a trilogy against fellow legend Fedor Emelianenko. The two heavyweights fought three times in PRIDE, between 2003 and 2004. Nogueira went 0-2 against Emelianenko, as one of the bouts was ruled a no-contest due to an accidental head-butt.

The Brazilian made his UFC debut in July 2007. He won the interim title in his second UFC bout by submitting Tim Sylvia via guillotine choke at UFC 81. He surrendered the title to Frank Mir in late 2008.

A three-fight skid in recent years brought Nogueira's overall UFC record to 5-6. He has several memorable moments during that stretch, including a riveting unanimous decision against former two-division champion Randy Couture at UFC 102 in August 2009 in Portland.

Following a recent three-round decision loss to Stefan Struve at UFC 190, UFC president Dana White stated his desire to see Nogueira, who has battled a multitude of injuries late in his career, hang up his gloves.

On Tuesday, he spoke on Nogueira's new role at the UFC.

"Big Nog is a legend in the sport of MMA," White said. "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 athlete and the sport as an ambassador. I look forward to working with him in this new chapter of his life."