By Chris McKenna, courtesy of The Daily Star

SUGAR RAY LEONARD believes Manny Pacquiao will show he has one more big fight left in the tank.

The boxing icon has backed the Filipino puncher to prove doubters wrong when he takes on Floyd Mayweather Jr on Saturday night in Las Vegas for the WBC, WBO and WBA welterweight titles.

Pacquiao, 36, is the underdog for the $400 million bout despite winning world titles in eight different weight divisions and being one of the best of his era.

He is being written off because of his KO defeat by Juan Manuel Marquez in 2012.

But Leonard has his own experience of being dismissed ahead of a huge fight.

The five-weight world champion had fought just once in five years before he faced Marvellous Marvin Hagler at middleweight in 1987.

He retired in 1982 after defending his WBC and WBA welterweight titles against Bruce Finch because of a detached retina.

But the American returned two years later to beat Kevin Howard in a non-title clash before beating Hagler in a cracker.

He said: "All fighters have one last fight in them, if you look [Muhammad] Ali against George Foreman. Ali won despite being expected to lose.

"With me it was Hagler, I knew I had one last fight in me. I believe that all applies to Manny Pacquiao.

"Maybe Floyd doesn't know exactly what power Pacquiao has, I did not know what power Hagler had until I was in there and he landed.

"I went there against Hagler, I just did not want to lose, there was so much at stake. But that is what makes fighters great, that is what makes fighters champions."

Leonard also believes Pacquiao's chances are boosted by Mayweather's ageing 38-year-old legs.

He said: "Has Floyd slowed down? Yes, I don't care who you are, everyone slows down and maybe Pacquiao can take advantage.

"Fighters themselves don't think they have slowed down, they just don't notice it."

But he does have one word of warning for Pacquiao - protect the fortune he is going to earn for this fight.

The Filipino is known as a generous man and has given millions to his compatriots as he works towards eventually being his country's leader.

Leonard blew most of his fortune through a lavish lifestyle and his own generosity to others

"Pacquiao tries to help everyone just like me," said Leonard. "He goes out of his way to help everyone but you can't help the world.

"Sometimes you have to say no. It was difficult for me to say no at first, I gave away many millions of dollars.

"When you become world champion you make an impact inside the ring, but you make a bigger impact out."

The former world champion has been involved in some of the sport's biggest fights, including his wars with Tommy Hearns and Roberto Duran.

But he will be among the punters at ringside on Saturday and just as excited as them.

He added: "On the night my palms will be sweating just like the fans. I am looking forward to this more than any other fight in recent years."