UFC 123: Rampage vs. Machida was a mixed martial arts event held by the Ultimate Fighting Championship on November 20, 2010 at The Palace of Auburn Hills in the Detroit suburb of Auburn Hills, Michigan. It was the first UFC event in the Metro Detroit area since UFC 9.

Before the start of the card, Jose Aldo was awarded the UFC Featherweight title by Dana White.

UFC 123 featured preliminary fights live on Spike TV.

On October 13, Rory MacDonald had to withdraw from his fight against Matt Brown. He was replaced by Brian Foster.

Gabe Ruediger was scheduled to face Paul Kelly, but was forced off the card with a groin injury on October 25. T.J. O'Brien replaced Ruediger.

Darren Elkins withdrew from his matchup with Edson Barboza and was replaced by Mike Lullo.

Fighters were awarded $80,000 bonuses.

A formal complaint was filed with Michigan's Unarmed Combat Commission regarding the timekeeping of the Harris-Falcão match. Near the end of the first round, Falcão was choking Harris. The allegation is that the timekeeper ended the round six seconds early and in turn had the round not ended early, Falcão may have successfully choked out Harris. Despite Falcão ultimately winning the fight by decision, the formal complaint was filed on January 13, 2011.

Lyoto Carvalho Machida (Portuguese pronunciation: [liˈotu maˈʃidɐ]; born May 30, 1978) is a Japanese-Brazilian mixed martial artist from Salvador, Bahia, Brazil who fights as a light heavyweight in the Ultimate Fighting Championship. He is a former UFC Light Heavyweight Champion and is currently ranked as the #6 light heavyweight fighter in the world by Sherdog, MMAWeekly and Yahoo! Sports.

Machida was born in the city of Salvador as the third son of the highly ranked head of the Brazilian branch of the Japan Karate Association, Shotokan karate master Yoshizo Machida. Yoshizo moved to Brazil from Japan when he was 22 years old. There he met and married Lyoto's mother, Ana Claudia. Growing up in Belém, Lyoto began training in karate at the age of three and earned his black belt at the age of thirteen. He also began training in sumo at twelve and Brazilian Jiu-Jitsu at fifteen. He won a number of amateur karate tournaments, including the 2001 Pan American Karate tournament.

He was the runner-up in the 2000 Brazilian Sumo Championships in the 115 kg division. As an adult, he became Brazilian Champion twice under Taylor Swanson, and placed second in the South American Championship. He defeated American black belt Jiu-Jitsu fighter Rafael Lovato Jr. at L.A. Sub X. In addition to his sumo and karate achievements, he has a college degree in Physical Education. Lyoto's brother, Chinzô, is a Shotokan vice-champion (Australia 2006), losing only to number-one ranked Shotokan master Koji Ogata. Lyoto and Chinzô fought in a Karate Final 10 years ago in which Lyoto gave Chinzô a cheek scar that still exists today. His other brothers include Kenzo Machida, a TV journalist for one of Brazil's biggest TV stations, Take Machida and adopted brother Francisco Machida.

Dana White (born July 28, 1969) is the current President of the Ultimate Fighting Championship (UFC), a mixed martial arts organization based in the United States.

Born in Manchester, Connecticut on July 28, 1969, White grew up in Las Vegas, Nevada, Ware, Massachusetts and Levant, Maine. White is a passionate Boston Red Sox fan. During his youth, he bounced back and forth between Boston and Maine. He attended the University of Massachusetts Boston but did not finish; however, while there he did launch a boxing program for inner-city youth.

White has a background as an aerobics instructor. In 1992, White established Dana White Enterprises in Las Vegas. He conducted aerobics classes at three gyms in the Las Vegas area and began managing MMA fighters Tito Ortiz and Chuck Liddell.

While working as a manager, White learned that Semaphore Entertainment Group, the parent company of the UFC, was looking for a buyer for the UFC. White contacted childhood friend Lorenzo Fertitta, an executive at Station Casinos, and a former commissioner of the Nevada State Athletic Commission. Within a month, Lorenzo and his older brother Frank bought the UFC, with White installed as its president. White currently owns about 9% of Zuffa, LLC, the entity the Fertitta brothers created to own and manage the UFC.

Karapet "Karo" Parisyan (Armenian: Կարո Փարիզյան; born August 28, 1982) is an Armenian-American mixed martial artist. From his days as a UFC mainstay, Karo holds notable wins over Ryo Chonan, Shonie Carter, Drew Fickett, Matt Serra, Nick Thompson, Chris Lytle, Nick Diaz and Antonio McKee.

Parisyan was born in Yerevan, Armenian Soviet Socialist Republic. His family migrated to America when he was six years old. Parisyan started training in Judo when he was nine years old under fellow Armenian Gokor Chivichyan. Parisyan stated that his father began taking him to Judo lessons because he beat up on his sisters and Judo would be an effective outlet for Parisyan to take out his anger. In a book he published, however, Parisyan wrote that his father introduced him to judo to cure his laziness. By age 10, Parisyan was training his Judo under both Chivichyan and Gene LeBell.

For more than thirteen years, Parisyan developed under the Hayastan Grappling System, a style developed by Gokor Chivichyan and Gene LeBell, which blends elements of Judo, Sambo, Catch Wrestling, Greco-Roman and Freestyle wrestling. Parisyan continued to train at the Hayastan Academy under Gokor and Gene until late 2005. In early 2012, Karo mentioned in an interview that he has returned to the Hayastan Academy.

Michael Gavin Joseph Bisping (born 28 February 1979) is an English mixed martial artist. He fights in the middleweight division of the Ultimate Fighting Championship and is the former Cage Warriors Fighting Championship Light Heavyweight Champion, former Cage Rage Light Heavyweight Champion and The Ultimate Fighter 3 Light Heavyweight Tournament winner. As of March 2012, Bisping is ranked the No. 4 middleweight in the world by Sherdog.

Bisping was born in manchester UK in 1979, but moved to Bridlington, East Yorkshire, England when he was a child. Taking an early interest in martial arts, Bisping began training in a traditional form of jiu-jitsu known as Yawara Ryu under Paul Lloyd Davies when he was 8 years old. In 1994, at the age of 15, Bisping competed as an amateur in England's first "no holds barred" competition, a precursor to modern MMA, called Knock Down Sport Budo (KSBO), organised by Davies.

At the age of 18, Bisping decided to abandon his martial arts training in order "to pursue real life". But less than a year later Bisping began training kickboxing and karate on the advice of Alan Clarking, owner of Black Knights gym, who saw potential in the young fighter. Bisping enjoyed a short, but successful kickboxing career, winning the North West Area title and later the Pro British light heavyweight kickboxing title. After again briefly quitting competition in 1998, Bisping returned to kickboxing to take the Pro British light heavyweight title for a second time. Soon after winning his second kickboxing title, Bisping was forced to abandon his full-time training for a "real job". Bisping worked in factories, slaughterhouses, as an upholsterer, a postman, a tiler, a plasterer, a double-glazing door salesman,production line operative making barbecues at Rectella in Clitheroe and also a relatively successful DJ around the north-west club scene.