UFC 53: Heavy Hitters was a mixed martial arts event held by the Ultimate Fighting Championship on June 4, 2005, at the Boardwalk Hall in Atlantic City, New Jersey. The event was broadcast live on pay-per-view in the United States, and later released on DVD.

This event was originally scheduled to take place at the Yokohama Arena in Japan with an Interim Heavyweight championship bout between Andrei Arlovski and Mirko Filipović serving as the main event. However the lack of sponsorship for the event forced the event to be moved to Atlantic City.

Initially, former champion Ricco Rodriguez was slated to contend for the heavyweight championship, but withdrew from the bout, citing complications with his training camp. Headlining the card opposite of interim heavyweight champion Arlovski, instead, was Miletich protégé Justin Eilers. Although there was some criticism directed at the UFC for giving Eilers a title shot after coming off a knockout loss to Paul Buentello at UFC 51, the UFC explained that Buentello was not medically cleared to fight when the main event was originally scheduled.

Diego J. Sanchez (born December 31, 1981) is an American mixed martial artist (MMA) of Mexican descent, with a background in wrestling and Gaidojutsu, system of submission wrestling developed by his longtime trainer Greg Jackson. He currently fights as a welterweight with the Ultimate Fighting Championship (UFC). Sanchez is currently ranked as the #9 welterweight fighter in the world by MMAWeekly.

Sanchez was born in Albuquerque, New Mexico. He attended Del Norte High School, where he became a state champion wrestler.^{[citation needed]}

Diego Sanchez wrestled in New Mexico before starting training MMA while working for UPS. Sanchez eventually joined Jackson's Submission Fighting, still while working for UPS, managing the time between work and training. In 2002, he made his MMA debut for King of the Cage where he also later became a champion.

His UFC debut came when he was chosen as a participant on the first season of the reality show, The Ultimate Fighter. Presented as a young, focused middleweight who only had one goal, to become a UFC champion, he won a contract with the UFC after winning a fight against Kenny Florian, becoming the middleweight winner for the first season of the show. On the show, Sanchez was known for being the "odd-ball" of the group, practicing yoga at odd moments and trying to extract "energy" from a lightning storm, and was also a self-proclaimed "Zen master". Sanchez' last fight before his loss to Josh Koscheck was against Joe Riggs on December 13, 2006 at UFC Fight Night 7. Sanchez landed a right hook that knocked Riggs down, followed by a running knee that knocked Riggs out. Sanchez won at 1:45 of the first round, scoring the first UFC knockout of his career.

Cub Swanson (born November 2, 1983) is an American mixed martial artist (MMA). He is currently signed as a featherweight with the Ultimate Fighting Championship.

Swanson made his WEC debut on March 24, 2007 with a victory over Tommy Lee by guillotine choke. He has also defeated Micah Miller. Following an eleven fight winning streak, Swanson lost to former UFC champion Jens Pulver, who was making his WEC debut. Swanson was forced to tap out at just 0:35 of round one due to a guillotine choke after attempting a single leg take down.

Swanson defeated Hiroyuki Takaya via unanimous decision in a bout that earned Fight of the Night honors at WEC 37.

Swanson was scheduled to fight Diego Nunes on the undercard at WEC 40, but Nunes was forced to withdraw from the fight just days before the bout because of a hand injury. Swanson lost to Jose Aldo by technical knock out via flying knees 8 seconds into the first round at WEC 41 on June 7, 2009.

Swanson defeated John Franchi on November 18, 2009 at WEC 44, winning Fight of the Night honors. In his bout against Franchi, Swanson broke both of his hands.

Junior dos Santos Almeida (Brazilian Portuguese pronunciation: [ˈʒũnjoʁ dus ˈsɐ̃tus]), also known as Junior Cigano ("Gipsy"; born September 12, 1984), is a Brazilian professional mixed martial artist and the current UFC Heavyweight Champion. He is ranked as the number one heavyweight fighter in the world by numerous media outlets.

Dos Santos started training Brazilian Jiu-Jitsu under Yuri Carlton for fitness reasons. After some time he was invited to join an MMA practice, where he met his boxing coach Luiz Carlos Dórea, and after roughly a year he made his debut fight.

Dos Santos became professional in 2006 at the age of 21. He fought in small promotions in Brazil, such as Demo Fight, Extreme Fighting Championship, Minotauro Fights and Mo Team League. He won 6 out of his first 7 bouts, suffering his only loss to Joaquim Ferreira, a fighter he'd previously beaten.

Dos Santos debuted for the UFC on October 25, 2008 at UFC 90. Considered a major underdog, dos Santos knocked out top contender Fabricio Werdum at a minute and twenty-one seconds of the first round with a strong uppercut, earning himself a "Knockout of the Night" award.

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.