Zou Shiming won his second professional fight at Fists of Gold II with a unanimous decision over teenager Jesus Ortega at the Venetian CotaiArena last night. But fans were still left wondering when the two-time Olympic gold medallist will really step it up and win inside the distance. Zou certainly looked sharper and faster as he landed punch after punch against the gritty 19-year-old, who did not seem intimidated by his much more heralded opponent. The battle started fast and furious and ended with a slugfest, but there was still no knock down or knockout by the 32-year-old, who just was not able to land the killer punch. In his first bout since his successful professional debut in April, Zou was moving fast and furious in the first round. There was no showboating or hands down, as he began aggressively and never let up in the six-round flyweight contest. But Ortega, who was carefully handpicked by promoters Top Rank and lost his second professional fight from five bouts, was a surprise. Unlike his last fight against Eleazar Valenzuela, Zou this time did not finish the fight with his face unblemished. Ortega managed to connect several good punches to Zou's head and the Olympic champion was sporting a bruised left eye even before the third round. Mexican Juan Estrada also made a successful defence of his WBO and WBA titles, defeating gritty Filipino Milan Melindo by a unanimous decision. Estrada handed Melindo his first defeat in 29 fights, winning the last two of the 12 rounds in superb fashion. Rising heavyweight Andy Ruiz Jnr had one of the most impressive victories, sending fellow American Joe Hanks to the canvas in the fourth round and winning the clash of the titans by a technical knockout. Ruiz, a portly 254-pound knockout artist, showed he had a great future as he dominated, delivering a devastating left and then right hook that saw Hanks crashing through the ropes. "I feel so good tonight and I worked hard up to this point. It's a dream come true for me. I threw a couple of jabs and he was getting tired. I threw a big right on the chin and I got him," said the soft-spoken 23-year-old, who won the WBO intercontinental heavyweight title and extended his record to 20-0, 14 KOs. Filipino Dave Penalosa knocked out Thailand's Ngaotawa Sithsaithong in a super bantamweight contest. Penalosa extended his win record to 6-0, 4 KOS after finishing with a huge uppercut that floored his opponent in the third round.