Manny Pacquiao has been told to show Juan Manuel Marquez no mercy when he puts his WBO welterweight title on the line against the Mexican at the MGM Grand in Las Vegas on Saturday night.
Mulltiple champion Pacquiao beat Marquez by a single point in 2008 and was held to a draw four years earlier by the three-weight champion.
Southpaw Pacquiao, 53-2-1 (KO 38), who returns to the ring after one-sided points wins over Shane Mosley, Antonio Margarito and Joshua Clottey, has been urged by trainer Freddie Roach to finish off Marquez in style and remove any lingering doubts from their previous two fights.
"I believe all fights should end in a knockout," said Roach. "Manny is a compassionate guy and he let the last two guys off the hook. I urge him not to be compassionate in fights because one punch can change a fight.
"Fighters always think they won. Both fights were close fights but the judges did their jobs. Obviously, he thinks he won. But you don't go to his hometown in the Philippines and campaign against the guy.
"He's been a little bit meaner to his sparring partners and his attitude is a little bit more aggressive," added Roach.
"He wants this fight badly especially after Marquez wore the 'Marquez Beat Manny Twice' t-shirts and went to the Philippines to campaign for another fight. I think Manny is going to pay him back."
"If Manny puts him down I don't think he will get up."