For Puerto Rican champion Miguel Cotto (34-1, 27 knockouts) and Filipino challenger Manny Pacquiao (49-3-2, 37 KOs), there never has been a more career-defining moment than this one.
Each will be battling for the pride of his countrymen as well as his status among boxing's best fighters, pound-for-pound, when the combatants step into the ring for Saturday night's mega-fight at The MGM Grand In Las Vegas.
After the jump, some of the most knowledgeable sources in the boxing world offer their predictions for a clash at the same site where Floyd Mayweather easily decisioned Mexican great, Juan Manuel Marquez, in September.
Joe Calzaghe, former supermiddleweight, light heavyweight champ
Manny Pacquiao by decision: I think Manny Pacquiao is going to be too quick for Cotto. I was ringside when Cotto fought [Joshua] Clottey.
He seemed to struggle a bit in that fight and it is hard to say what he will do against a faster, quicker Pacquiao. I know people say Cotto is the bigger guy, but I still think Pacquiao beats him in a decision.
Hector Camacho Sr., former WBC and WBO three-division champ
Manny Pacquiao to win: I'm a Puerto Rican like Cotto, but I like Pacquiao because he has fought better guys, like Oscar De La Hoya. I see him having no problem against Cotto.
Cotto is not a smart fighter, he boxes, and he's shown his colors already. He can be beat. So can Pacquiao. But I like Pacquiao. He has an unorthodox style, with punches coming from all over. Cotto tries to box. I see Pacquiao possibly stopping him.
Pacquiao's on a roll. He has the confidence. He has the boxing momentum. I see him winning.
Chad Dawson, undefeated IBO and WBC interim light heavyweight champ
Manny Pacquiao to win: Manny Pacquiao. He's the best. He's on top right now.
Bernard Fernandez, Philadelphia Daily News
Miguel Cotto by decision: I initially picked Pacquiao, but I did a flip-flop on this one. For a guy that started at 106, you have to figure he's going to climb up one division too high at one point.
Cotto is not an Oscar De La Hoya at the end of the line, and he's not Ricky Hatton. He's one of the top five or six in the world, and he's a natural welterweight. I'm picking Cotto by decision.
His strength is going to be too much. Pacquiao keeps surprising me, but this may be the fight where he goes up one weight class too many.
Doug Fischer, co-editor of RingTV.com
Manny Pacquiao by decision: I think it's going to come down to styles. As versatile a boxer as Cotto is, he's predictable. The version of Pacquiao we've seen recently is the definition of unpredictable in the ring.
Pacquiao has a non-stop mix of in-and-out movement, feints, sneaky jabs and explosive lead power punches. His opponents never know what he's going to lead with, and so far, no one since Juan Manuel Marquez has been able to time this guy.
I think Cotto will eventually catch Pacquiao, which is why I think the fight will go the 12-round route. I believe Pacquiao will rock Cotto repeatedly in the early rounds with power punches that catch the bigger man blind.
But I also believe that the Puerto Rican star will be most dangerous while hurt. Pacquiao's instincts are to jump on a wounded prey, but Cotto will catch Pacquiao coming in and earn respect.
From the middle rounds on, I think the two will go at it. Pacquiao will use his legs to get in and out with fast combos and to stay off the ropes, while Cotto stalks forward and does damage with his stiff jab and occasional right hands that find the smaller man's body and head.
Pacquiao will constantly move to his left, taking Cotto's lethal left hook out of the equation. After 12, excellent rounds, I believe Pacquiao will have had more moments in the fight, and will win a close decision.
Nancy Gay, FanHouse.com
Manny Pacquiao by decision: This is Manny Pacquiao's toughest opponent to date-- a pure boxer and a natural welterweight who has the strength to inflict real punishment if he stays busy and works the body.
Miguel Cotto has a lot to prove after the hideous beating by Antonio Margarito. Does he have the chin to take punches? Can he stay off the ropes and maintain stamina through 12 rounds?
The catchweight of 145 pounds is lighter than Cotto would like, while Pacquiao's impressive hand and foot speed hasn't diminished the bigger he gets.
I think Pacquiao's speed, along with his superior trainer and corner, will prevail, and boxing's pound-for-pound champion will win by decision.
Bernard Hopkins, future Hall of Famer and former two-division world champ
Manny Pacquiao to win: Pacquiao is going to chop Cotto up. Out of respect, Cotto will get some rounds, but Manny is the Bruce Lee of boxing.
His basketball and martial arts background give him that speed and agility. You can't tell where his shots are coming from. Unlike Rocky, Bruce Lee was a real dude and so is Manny.
Kevin Iole, Yahoo! Sports Boxing
Manny Pacquiao by decision: I am afraid Miguel Cotto isn't the same man since he lost to Antonio Margarito. There is a suspicion that Margarito's gloves may have been loaded in that fight, but it's never proven.
But what is fact is that Cotto has slowed greatly since that bout. If I were convinced Cotto was going to be the same guy he was before he fought Margarito, I'd take him. But I think he's slowed because of the damage he took in that fight.
As a result, I expect Manny to move in and out, hitting Cotto and sliding out of danger. I think Pacquiao's quickness will make the difference and he'll win a unanimous decision.
Chris Mannix, Sports Illustrated
Miguel Cotto by decision: Pacquiao has enjoyed a meteoric rise by beating on offensive-oriented fighters [such as] David Diaz, Oscar De La Hoya and Ricky Hatton. But Cotto will be the first true counter-puncher he has faced since Juan Manuel Marquez.
Cotto has the speed and skill to deflect Pacquiao's heaviest shots, and the power in both hands to return a few of his own. Expect a back-and-forth, uber-competitive fight that is worth every dollar of the Pay Per View price. But expect Cotto to emerge with the decision.
Shane Mosley, WBA super world welterweight champ
Miguel Cotto by decision: It's going to be an interesting fight, and I think Pacquiao better take it very seriously. I think Cotto will win because he's a little bit bigger and is a real welterweight.
His power may be enough to overcome Pacquiao's speed. I think Cotto wins in a decision.
Kiernan Mulvaney, ESPN.boxing and Reuters
Manny Pacquiao by decision: I am having an incredibly hard time picking this fight. I think it's a very close, very even fight that, funny as it may sound. I can picture either guy totally dominating.
Miguel Cotto is one heck of a fighter: He's strong phsyically, he's strong-willed, he's calm, and he's a very good boxer technically. Until Antonio Margarito's possibly loaded gloves started taking their toll, Cotto was winning that fight last year with ease, I thought.
But I'm not sure Cotto is quite the same fighter he was before that. I think he just that little bit more vulnerable than he was. And Cotto, more than most fighters, really likes to set his own pace, to stamp his authority early on and force his opponent to fight at the speed he wants.
That isn't going to happen against Manny Pacquaio, and so, even though I can also see Cotto punishing Pacman with far harder shots than the Filipino has ever felt, I think Pacquiao's swarming fusillade proves too much, and Pacquiao winds up taking a hard-fought but ultimately clear decision.
Carlos Oritz, Hall of Famer and former three-time world champ
Miguel Cotto by decision: Pacquiao is a good boxer, but Cotto is a fighter. I'm going to give the edge to Cotto, and not just because he's Puerto Rican, but because of the way he fights.
He always comes to fight, he's always in shape. Cotto is going to have the edge. I see him winning by decision, but I do think he can knock Pacquiao out if the chance arrives.
Michael Davis Smith, FanHouse.com
Manny Pacquiao by 11th-round technical knockout: Miguel Cotto is bigger than Pacquiao, more powerful than Pacquiao, and seems to me more motivated than ever since his loss to Antonio Margarito last year.
But I just don't think he's ever seen anything like Pacquiao's blinding speed, and I think that will be the difference in this fight. I'm picking Pacquiao by 11th-round TKO.
Tim Smith, New York Daily News
Miguel Cotto by decision: Cotto in a decision. He is the first,legitimate welterweight that Pacquiao has faced who is in his prime rather than a blown-up junior welterweight or a fighter who is no longer in the prime of his career.
Bert Sugar, noted boxing historian
Manny Pacquiao by eighth round knockout: This is a fight of speed and accuracy for Pacquiao, against the body punching of Cotto. Vegas has always been Pacquiao's home, and the Evel Knievelof boxing will leap over another opponent to come away with the win.
Pacquiao also has a secret ingredient called [trainer] Freddie Roach, whose battle plans bring tears to the eyes of Robert E Lee. Cotto is a gutsy and gritty fighter, but I think Pacquiao stops him on cuts, and wins in the eighth round.
Felix Trinidad, former three-division world champion
Miguel Cotto by decision: Manny is a big puncher and a good boxer, but he has never faced a natural welterweight like Miguel. Cotto is the most dangerous fight of Pacquiao's career.
Mike Tyson, former undisputed world heavyweight champ
Manny Pacquiao by mid-rounds knockout: I pick Manny Pacquiao by knockout. I think he will knock him out in seven or eight. Manny just has too much for Cotto.
Winky Wright, former undisputed junior middleweight champ
Miguel Cotto by decision: If Cotto stays busy, he'll win a decision. I think that Cotto will win the fight, but I thinks it's gonna be a good fight.
On the night of the fight, Pacquiao will still not be a full welterweight. And Cotto is very strong. As the fight plays out, around rounds seven, eight, nine, that's when Cotto starts taking over.
I think Cotto will win by a decision, but he might even get a knockout. With all of my heart I think Miguel Cotto will win.
The boxing experts have chosen Manny Pacquiao to win, 11-7, with a 5-4 advantage for the Pac Man among the nine former or present world champions.
Check back on Friday for my analysis and prediction.