Manny Pacquiao says he will use his speed to end Floyd Mayweather's unbeaten streak in Las Vegas on Saturday.
Mayweather boasts a perfect 47-0 record going into the showdown at the MGM Grand but Pacquiao says he has never been tested as he will be in his 48th fight.
"I'm different to the 47 opponents he has fought before. I'm faster than them and I'm content for the fight. I believe this is the moment he will experience his first loss," Pacquiao said.
"I can't say Mayweather is the most dangerous opponent of my career because I've fought guys like Oscar De La Hoya, Miguel Cotto, Juan Manuel Marquez and other boxers.
"He's a difficult opponent but my confidence is different for this fight. This is one of the most important fights for my boxing legacy."
Pacquiao was speaking at a gathering of more than 1,000 fans at the Mandalay Bay resort after organising his own 'welcome to Vegas' event rather than join Mayweather at the official Grand Arrival event a few hundred yards down the Strip.
A DJ, Filipino dancing band and singer took it in turns to entertain the crowd until Pacquiao arrived 44 minutes late alongside trainer Freddie Roach and promoter Bob Arum.
Pacquiao enters the richest fight in boxing history as underdog for the first time since his eight-round destruction of Oscar De La Hoya in 2008, but he is happy for Mayweather to be favoured.
"I have to prove something. Every time I'm the underdog, I like that because my killer instinct, my focus is there. This is what I want," Pacquiao said.
"We're not working one strategy, but we have two or three. If he wants to fight me, that's good for me.
"But if he's running and running and moving around the ring, we've prepared for that."
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