against Pinduka, he started training in Brazilian jiu-jitsu with Osvaldo Alves. Later he trained Joe Moreira before his fight against the Russian boxer Yuri Vaulin. Seeing his good skills in grappling, Moreira gave him a black belt in Brazilian jiu-jitsu and caused a commotion and controversy among his fellow Brazilians, due the rivalry between the two martial arts. His instructors included Euclydes Hatem. Eventually, Ruas became famous among the Brazilian martial arts circle and one of the most regarded non-BJJ fighters in Brazil due his philosophy of Cross-Training and in synthesizing all martial arts he knew for both Vale Tudo contests and self-defense into a new hybrid martial art he dubbed "Ruas Vale Tudo". However, this philosophy also caused controversy among Brazilian fighters and he was labelled as a Creonte by not only BJJ but also by Luta Livre fighters. In 1991 he was going to participated in Desafio - Jiu Jitsu vs Luta Livre, an event fought as a challenge between fighters from the two martial arts, Ruas was cast to fight BJJ representative Amaury Bitetti but cancelled his participation and Bitetti was declared winner by W.O. Instead, in 1992 he promoted his own event in Manaus where he defeated Francisco Borges with a rear naked choke. Eventually he attracted the attention of Brazilian manager and fight promoter Frederico Lapenda and was able to get the 34-year-old fighter into the Ultimate Fighting Championship. Ruas debuted in the Ultimate Fighting Championship at the UFC 7 event in 1995. He firstly faced Larry Cureton, who outweighed him by 40 lbs, but Ruas submitted him with a heel hook after a methodical grapple. His next opponent was the judoka Remco Pardoel, who early tried a guillotine choke, but Ruas blocked it and grinded him with foot stomps. After a failed heel hook attempt, Ruas controlled Pardoel and attacked him with knees and punches on the ground, making him tap out. Ruas's final fight was against 6'8", 330 lb Paul Varelans, and he showed his muay thai skills by overwhelming Varelans with punch combos and repeated leg kicks. He also used again his characteristic foot stomps when Paul clinched him against the cage. At the end, Varelans could not take more kicks to his legs and fell to the ground, where Ruas pounded him until the referee stopped the fight, giving Ruas the victory of the tournament. Thanks to his victory in UFC