Manny Pacquiao has told Juan Manuel Marquez he must prove he can win when the two meet once again in the ring this weekend.
The pair have fought three times previously, most recently 13 months ago in the same MGM Grand ring where they will meet on Saturday night.
Officially, the tally stands at two Pacquiao wins and one draw, though many fans and boxing writers believe Marquez could legitimately have won all three encounters.
But the Filipino says he is frustrated by his opponent's insistence that he was the deserved winner of their previous three contests,
"He always claims he won the fights," said Pacquiao, who has won world titles in eight weight divisions. "So he needs to prove something.
"You cannot say, 'Yes I won the fight' when you are always backing off. It's contradictory. If you're claiming you won the fight, then you have to press the action."
The rivalry between the pair almost failed to last one round, after Pacquiao dropped Marquez three times in the opening round of their first meeting in 2004, before the Mexican rallied to outbox his opponent and eke out a draw.
In their second meeting four years later, Pacquiao knocked down Marquez in the third round, which proved the difference after he won a close split decision.
When the fighters last met, Pacquiao narrowly retained his WBO welterweight title with a controversial majority decision and boos from disgruntled Marquez fans echoed around the arena after the shock decision was announced.
The Mexican, for his part, affirmed his belief that he had been unfairly defeated in their previous encounters.
"I want them to raise my hand," Marquez said.
"People tell me, 'You really beat him', in the last three fights. A lot of people feel I beat him.
"But I want to have my hand raised. I want the judges to really look at what they're doing and get it right this time."
"When you say 'Muhammad Ali', you think 'Joe Frazier'," the Filipino said. "And I think when you say 'Manny Pacquiao', you think 'Juan Manuel Marquez'. And when you say 'Marquez', you think 'Manny Pacquiao'."
But neither man is expecting a fifth fight, whatever happens in the ring on Saturday. The fourth bout, they insist, will be the last.
"This is the last fight with Manny," said Marquez. "I don't know what will happen in the ring, but this is the last time."
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