the "new Three Musketeers". Nakamura began training vale tudo and on December 31 made his mixed martial arts debut in a fight, where he was defeated by Daniel Gracie via submission to an armlock. Nakamura's second MMA fight took place on May 2, 2003, when he defeated Jan Nortje with a guillotine choke. He followed that up on September 13 with another submission victory over Shane Eitner in his third MMA fight. On December 9, Nakamura defeated Hiroyoshi Tenzan for the IWGP Heavyweight Championship, thus becoming the youngest wrestler in history to win the title. On January 4, 2004, at Wrestling World 2004, Nakamura successfully defended the IWGP Heavyweight Championship against the NWF Heavyweight Champion Yoshihiro Takayama in a title unification match. However, Nakamura was forced to vacate the title due to an injury just a month later. Upon his return, Nakamura received a shot at the title, now held by Bob Sapp, but he was defeated by the defending champion on May 3. Later that month, Nakamura competed in his last MMA fight, defeating Alexey Ignashov with a forearm choke on May 22. On December 11, Nakamura and his tag team partner Hiroshi Tanahashi defeated Kensuke Sasaki and Minoru Suzuki in a decision match to win the IWGP Tag Team Championship. On January 4, 2005, at Toukon Festival: Wrestling World 2005, Nakamura defeated his own tag team partner to win the IWGP U-30 Openweight Championship. During their tag team title reign, the two left for an excursion to Mexico, where they feuded with Los Guerreros del Infierno and defended the IWGP Tag Team Championship against Rey Bucanero and Olímpico. On October 30, they lost the IWGP Tag Team Championship to Cho-Ten (Hiroyoshi Tenzan and Masahiro Chono). Excursion and return (2006–2009) Nakamura challenged Brock Lesnar for the IWGP Heavyweight Championship on January 4, 2006, at Toukon Shidou Chapter 1, but he lost. In March 2006, Nakamura announced that he would depart on a learning excursion to further improve his wrestling skills. Among other things, he would travel to Mexico, Brazil and Russia as well as train with Lesnar at Lesnar's personal gym to gain muscle mass. NJPW President Simon Inoki later suggested that as part of his learning excursion, Nakamura would be loaned to World Wrestling Entertainment (WWE) to gain experience in working large American shows. However, it proved to be mostly speculation and never came to pass as Nakamura