UFC 39: The Warriors Return was a mixed martial arts event held by the Ultimate Fighting Championship on September 27, 2002, at the Mohegan Sun Arena in Uncasville, Connecticut. The event was broadcast live on pay per view in the United States, and was the first UFC event to be released on DVD.

Headlining the event was a Heavyweight Title bout between Randy Couture and Ricco Rodriguez for the vacant title, which was stripped from Josh Barnett following a positive test for steroids.

The event marked the octagon debut of future UFC Heavyweight Champion Tim Sylvia. This fight saw Tim's opponent, Correira, take several straight punches, knees and kicks to the head without ever falling before his corner eventually threw in the towel.

The Rodriguez/Couture fight was one of only three fights in UFC history to end in the 5th round. The others were BJ Penn vs. Diego Sanchez at UFC 107 and Anderson Silva vs. Chael Sonnen at UFC 117.

Matthew John Serra (born June 2, 1974) is an American mixed martial artist and Brazilian Jiu-Jitsu black belt. He is a former UFC Welterweight Champion and an ADCC Submission Wrestling World Championship silver medalist. He began practicing martial arts at an early age, first studying kung fu. In the 1990s, he began studying Brazilian Jiu-Jitsu under Renzo Gracie and on May 23, 2000 he obtained his black belt, the first American to do so under Gracie. He is one of only two people in MMA to defeat Georges St-Pierre, the other being UFC Hall of Famer Matt Hughes.

Serra won first place at the Brazilian Jiu-Jitsu Pan American games in 1999 and won third place at the 1999 World Championships in Brazil as a brown belt. Continuing his Martial Arts career, he competed in the ADCC Submission Wrestling World Championship choking out Takanori Gomi, winning a decision over Jean-Jacques Machado, and placing 2nd in the 66–76 kg division. Serra was invited to compete in Pride 9 against Johil de Oliveira but the bout was called off at the last minute when Oliveira was burned in a pyrotechnics accident backstage. Soon after, Matt began to compete in the UFC organization where he built up a record of four wins and four losses. One of the losses was a close decision fight with future Welter and Lightweight champ B.J. Penn which would have earned him a title shot in the failed Lightweight tournament.

Nhat Nam Si Phan (born March 13, 1983) is an American mixed martial artist who competes in the featherweight and lightweight divisions. He was a competitor on The Ultimate Fighter: Team GSP vs. Team Koscheck. Currently, Phan is signed with the Ultimate Fighting Championship, fighting in their featherweight division.

Nam Phan takes pride in his Vietnamese heritage and is avid part of the Vietnamese-American community. He proudly displays both the American and South Vietnamese flag on his gi as a symbol of his pride in the freedom of his current home and of his lost homeland. Phan owns and runs the Madu Academy, where he teaches Brazilian Jiu-Jitsu as well as boxing and Muay Thai.

Phan began training in Taekwondo at the age of 4. By the age of 16, he had earned a 2nd degree black belt in Quyen Dao Vietnam, a Vietnamese combat martial art, and also holds a black belt in Karate. Phan then began studying jiu-jitsu in the year 2000. In 2005, Phan co-founded Ma Du Entertainment, a business to promote mixed martial arts fighters. He is also a professional boxer with a record of three wins and one loss.

Brandon Michael Vera (born October 10, 1977) is an American mixed martial artist. He competes as a light heavyweight in the Ultimate Fighting Championship. He is the winner of the WEC 13 Heavyweight Tournament and currently resides in San Diego, California.

Vera is the son of a Filipino father, Ernesto, and an Italian-American mother, Amelia. He grew up in a family with seven boys and three girls. He was born and raised in Norfolk, Virginia, and attended Lake Taylor High School where he excelled in wrestling and earned a four-year athletic scholarship to Old Dominion University. However, he dropped out of Old Dominion after a year and a half when he felt college was not for him, and enlisted himself in the United States Air Force.

In the Air Force, Vera joined the force's wrestling team and trained at the US Olympic Training Center in Colorado Springs, Colorado. His military wrestling career was cut short in 1999 when he tore ligaments in his right elbow. Arthroscopic surgery repaired the ligaments, but he had nerve damage from the experience, causing him to be unable to use his right arm. He was released from the Air Force on a medical discharge.

Din Yero Thomas (born September 28, 1976) is an American mixed martial arts fighter and part time break dancer, who was featured on The Ultimate Fighter 4. He currently runs two successful Brazilian Jiu-Jitsu and MMA academies in Port St. Lucie, Florida and is a black belt in Brazilian Jiu-Jitsu under Ricardo Liborio. Thomas fights out of Florida and trains with American Top Team.

Thomas has acted in local independent films, portraying The Fight Kid in Chris Fuller's Loren Cass and Reverend Pierce in Natalie, Queen of Scots.

Before entering the UFC, Din Thomas held a 12–1 MMA record including wins over future UFC lightweight champion Jens Pulver and Dokonjonosuke Mishima, with his only loss coming to future UFC lightweight title challenger Caol Uno. Thomas made his UFC debut at UFC 32, in a fight against future UFC lightweight & welterweight champion B.J. Penn, where he lost by TKO (Strikes) in Round 1. Thomas returned at UFC 33, defeating Fabiano Iha by unanimous decision.

At UFC 39, Thomas faced Japanese superstar Caol Uno in a rematch. The fight was part of a tournament to determine the new UFC Lightweight Champion. After three rounds, Thomas lost by unanimous decision. His next fight was a split decision victory over future UFC welterweight champion Matt Serra at UFC 41. This fight would prove somewhat controversial, due to one of the judges mistakenly placing the score he assigned to Thomas in the column reserved for Serra^{[citation needed]}. This caused Serra to be declared the winner by decision, but the mistake was discovered and Thomas and his team were notified of the change, giving Thomas the split decision victory. This would be Thomas's last UFC fight for 3 years.