LAS VEGAS – Juan Manuel Marquez sensationally knocked out Manny Pacquiao in the sixth round of their non-title welterweight bout at the MGM Grand in Las Vegas in the early hours of Sunday morning, earning his first win over the Filipino in four attempts.The 39-year-old Mexican, who had lost twice and drawn once in their three previous meetings, sent Pacquiao crashing to the canvas with a stinging right hand with one second left in the round.The Filipino southpaw fell face first and remained motionless for several minutes before finally getting up, smiling at Marquez and then shaking his opponent’s hand in middle of the ring.‘We knew it was going to be a very difficult fight but we knew it was possible to win,’ a beaming Marquez said ringside after improving his record to 55-6-1 with 40 knockouts.‘I threw a perfect punch,’ Marquez added. ‘I knew Manny could knock me out at any time.’Pacquiao, who had been knocked down in the third round, sent Marquez to the floor in the fifth and looked to be getting the better of the fight until the stunning knockout.‘He’s not an easy opponent,’ Pacquiao said after slipping to 54-5-2 with 38 knockouts.‘I did my best. I know that I got him in the last couple of rounds but I started to be over-confident and I got hit by a solid punch. I did not expect that punch. ‘I got hit by a punch I didn’t see.’Promoter Bob Arum immediately said he could see a fifth fight between the two boxers, and a dazed Pacquiao agreed. ‘Why not?’ he said.