Ruas is the founder of Ruas Vale Tudo, a hybrid of submission wrestling and kickboxing. He also used to train in the art of capoeira with renowned Mestre Camisa in Rio de Janeiro at the Santa Luzia club, downtown Rio. He has instructed fighters such as Pedro Rizzo and Renato Sobral. He is also a black belt in Luta Livre, who faced up a legendary quarrel against the Brazilian jiu-jitsu fighters in the 80s and 90s. After the match 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 among his fellow Brazilians. His instructors included Euclydes Hatem. Ruas debuted in Ultimate Fighting Championship at the UFC 7 event. 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 7, Ruas was invited to the Ultimate Ultimate event. He defeated Keith Hackney by choke with ease, but his next opponente, Oleg Taktarov, made a tougher contest. Both fighters used a passive approach to the fight, with Ruas blocking Taktarov's takedown attempts and seizing all the opportunities to strike him, actually making him bleed profusely. However, the judges gave the decision win to Taktarov, and Ruas was eliminated from the tournament. This decision was met with controversy, and Ruas and his cornermen appealed to the referee, but nothing came from it. A year later, he faced Taktarov again in Brazil, in a bout with no judges. The rematch ended in a draw, but Ruas was clearly the most dominanting fighter, and he shook hands with Oleg after the fight. He also won the World Vale Tudo Championship Super Fight belt in the process. He returned briefly to UFC to fight former heavyweight championMaurice Smith in UFC 21, but lost by TKO. Ruas suffered an injury in the first round and could not continue.
