Manny Pacquiao (52-3-2, 38 KOs) faces Shane Mosley (46-6-1, 39 KOs) for the WBO welterweight title on Saturday, and we've got the inside track on the clash...
Mosley will enter the ring in Las Vegas as an 11/2 underdog, and with his chances of victory widely written off - but energised by the knowledge that he once walked in Pacquiao's shoes, as the putative pound-for-pound king at the turn of the century.
The American was discussed as the planet's finest pugilist in 2002, having compiled a 38-0 record ahead of his clash against Vernon Forrest, a much taller welterweight with Olympic pedigree. Forrest beat him on points, then repeated the trick a few months later, setting into motion Mosley's gradual spiral from the summit of boxing.
He's broken the fall on a few occasions since then, notably when he stunned the world as a 4/1 outsider by stopping Antonio Margarito in 2009, but his last two outings have laid bare some stark truths about his decline. There was Floyd Mayweather Jnr, who took him apart on points, and then Sergio Mora, who battled to a split decision in a scrappy brawl. Mora has subsequently tasted defeat against Brian Vera, who had lost four of his last five going into that fight.
So, while we know Mosley is "really bothered" to be discussed as an unlikely victor, it's clear that his sense of grievance is unjustified. Even his trainer, Nazeem Richardson, has called it his "Buster Douglas v Mike Tyson moment", highlighting the stern test that he faces in Sin City, where they deal everything but fairytale endings.
What Mosley will be desperate to cling onto is his proud record of having never been stopped, which remains intact despite the odd moment of peril, particularly in the late stages against Mayweather, when his tank looked empty. If he can do that, there can be some pride in defeat, and his career will surely continue - but an early KO defeat leaves him staring at the prospect of hanging up those famous gloves.
If Pacquiao can stop him, the benefit will be two-fold: firstly, it gives him 14th straight triumphs, leaving his pound-for-pound supremacy unquestionable, and secondly, it means he will have outstripped his long-term rival Mayweather, which may coax the unbeaten American out of his retirement, or however we should term his current hiatus from the ring.

But Mayweather is "watching Lady Gaga on Saturday night", so there's no reason to suspect he'll take any notice of what looks set to be a comfortable Pacquiao victory.
Mosley, even at 39, is still sharp enough to ask a few questions of Pacquiao early on - and the Filipino can look vulnerable against speed - but, while he might land the odd telling counterpunch, it's likely he will eventually be drowned by the deluge of blows that Pacquiao can fire off with those lightning fists.
Frequent visits to the body are likely to reap rewards late on, with Mosley's ageing legs liable to betray him as the final bell creeps closer. There's just too much dynamite in Pacquiao's fists for this version of Mosley, a once-terrific fighter now spent at the highest level, to endure.
Prediction
Pacquiao by KO in the 11th - that's 12/1 with bet365.
The war of words
"We started in the mountains in the first day of training and he's been consistently trying to kill his body."
Trainer Freddie Roach quells any fears of complacency in the Pacquiao camp
"I'm not asking him to match Pacquiao's speed, but to be the best Shane Mosley he can be. This is a legend, not Johnny Far Down the Road. We won't get all gladiator with him like a young guy would, going down in flames."
Richardson warns his charge not to get carried away under the glare of the spotlight
"All he's doing is fighting my leftovers and he just keeps saying that I'm scared."
Mayweather takes another swipe at Pacquiao - but will they ever meet in the ring?
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