Juan Manuel Marquez insisted he was a "clean fighter" after his demolition of Manny Pacquiao. The Mexican, whose more muscular form drew attention before Saturday's bout, predicted drug tests in Nevada would come back negative. He also said he intended to do random, Olympic-style testing before his next fight. "I feel very happy with my training. I feel great about the tests," Marquez said from his Las Vegas hotel suite before boarding a flight home. "I won't have a problem." Marquez, 39, rallied from three bitterly contested fights against Pacquiao - two losses and a draw - to knock out Pacquiao with a precise right counter-punch late in the sixth round. His new muscular shape emerged in a training camp overseen by former steroid figure Angel "Memo" Heredia, who called Marquez a "Hulk" at a news conference last week. The Nevada State Athletic Commission did not perform a single random drug test on Marquez or Pacquiao during their training camps, and fight promoter Top Rank did not offer to pay the commission to conduct supplemental testing. Nevada collected pre-fight and post-fight urine samples from each fighter, and the results should be known by next Monday, said Keith Kizer, the commission's executive director. Marquez said he was irritated by speculation that his body did not develop naturally "after working hard for four months in Mexico". "If I continue fighting, I'd like to do Olympic-style anti-doping tests with my opponent." All indications are his next opponent will be Pacquiao. Promoter Bob Arum said earlier the gruelling nature of the fourth fight, and the expected greater interest in a fifth match, forces the showdown to be later than Pacquiao's originally planned date of April 20 for his next fight. The bout's payday would easily surpass Marquez's US$6 million guaranteed purse from Saturday, and his Mexican promoter Fernando Beltran said he expected Marquez to accept another Pacquiao fight. "I don't know what will happen," Marquez said. "But this fight, there was so much about people saying these things about me. I don't like to use substances. I didn't. I trained hard." Marquez spent the hours following his victory enjoying the victory "with my team, my Mexican people". He is scheduled to meet Mexican President Enrique Pena Nieto tomorrow and will present him with the gloves he used in the win over Pacquiao "I'm very happy I finished it by a knockout, because everyone knew what happened in my last three fights, and I never knew what was going to happen with the judges," Marquez said. "I won this fight myself. I won this victory. And I'm very happy." Beltran said the rest of Marquez's life would have been stained with some unhappiness if he had never beaten Pacquiao. "This fight is the most important one to me, I wanted to beat Pacquiao," Marquez said, when asked if he felt he placed too much importance on beating the Filipino. "Right now, I feel so good about that. It feels like the Mexican people are very happy, too."