By Jake Donovan

The biggest fight of the 21st century is finally upon. Five years of buildup are officially in the past as Floyd Mayweather and Manny Pacquiao are just hours away from their highly anticipated May 2 showdown at the MGM Grand in Las Vegas, Nevada.

The bout marks a rare occasion where the two best fighters in the world square off in the ring. In such instances, it was the welterweight division that has played center stage.

Talks of these two settling their differences in the ring first surfaced in 2009. Mayweather ended a 21-month hiatus with his ring return while Pacquiao became a full-time welterweight later in the year.

Negotiations were well on their way to leading to a head-on collision, only for talks to break down over drug-testing protocol. In the five years since, it's been an exhausting battle of both camps arguing over whose is bigger, while heading in their separate directions facing anyone other than each other.

From the fallout of their initial round of talks, Mayweather went on to reclaim the World welterweight champon he vacated upon his faux retirement in 2008. A 12-round win over Shane Mosley in their May '10 showdown saw Mayweather regain the championship he won in 2006.

Saturday will mark fifth defense of the welterweight crown under his current reign. During that time, Mayweather also owns wins over Miguel Cotto and Saul 'Canelo' Alvarez, both of which took place in the junior middleweight division.

The win over Alvarez netted the World junior middleweight crown, becoming just the second fighter in boxing history to win lineal championships in four weight classes.

The other fighter to do so? The man he will be sharing ring space with this weekend.

Pacquiao entered the history books in each of his two fights in 2009. His 2nd round knockout win over Ricky Hattom - which many insist is his best win among his Hall of Fame career - earned the World junior welterweight championship, after having held such honors at flyweight, featherweight and junior lightweight.

Six months later, the Filipino superstar knocked out Cotto in 12 rounds to claim a welterweight title, a record seventh weight class conquered. He would add to that total with a vacant junior middleweight title win over Antonio Margarito in 2010.

All hope appeared to be lost when Pacquiao was knocked out by Juan Manuel Marquez in their epic fourth fight in Dec. '12. Further driving a wedge between the two was Mayweather's defection from HBO - with whom Pacquiao remains faithfully aligned - for Showtime, signing a record-breaking deal estimated at more than $200 million.

Demand for the fight reached a fever pitch when both fighters saw a massive decline in Pay-Per-View sales in their four combined bouts in 2014. Talks floundered until the two fighters happened to attend the same Miami Heat game in late January. The meeting at center court during halftime sparked an incredible buzz, and a subsequent meeting in Pacquiao's hotel room allowed both fighters to know where the other stood.

One month later, the fight was signed and sealed, officially kicking off a stretch that leads to what will easily go down as the most lucrative event in boxing history.

Will Mayweather retain his perfect record he so greatly cherishes, to the point of an unhealthy fear of losing? Will Pacquiao overcome what appears to be disadvantages in every category not relating to power, and score the upset? Or will all involved have the last laugh, with the fight producing an unsatisfactory and anti-climactic ending and the night proving to simply go down as the greatest money grab in boxing history?

Read on to see how the staff at BoxingScene.com believes the biggest fight in boxing goes down tonight in Las Vegas.

BOXINGSCENE.COM STAFF PREDICTIONS: FLOYD MAYWEATHER vs. MANNY PACQUIAO

Ryan Burton (Pacquiao SD): I have a gut feeling that Mayweather goes down early, gets to his feet and we end up with a somewhat controversial victory. Pacquiao will throw a lot more punches but fans and insiders alike will debate if his quantity should give him the nod over the "quality" of Mayweather's more economical but effective punches.

Jake Donovan (Pacquiao Dec.): Pacquiao’s absolute best shot is to jump out to an early lead and then somehow do no worse than hold the line for the remainder of the fight. Floyd has shown a penchant for being slow to come out the gate in the past (most notably in wins over Oscar de la Hoya and Zab Judah), whereas Manny doesn’t have any real history of rallying from behind to win a fight, unless you count his overcoming a flash knockdown early to otherwise dominate and stop Marco Antonio Barrera in their first fight. If Floyd jumps out to a strong start, the fight is essentially over. I don’t see Pacquiao scoring a one-punch knockout, nor do I see Freddie Roach devising a game plan that calls for his fighter to ride out the storm. An early lead by Pacquiao could force Mayweather into a shell just enough to edge out a narrow decision, that will be debated for as long as fans still argue over Sugar Ray Leonard’s win over Marvelous Marvin Hagler nearly 30 years later.

Terence Dooley (Mayweather Dec.): I can't see anything other than a Mayweather win. He's by far the better boxer. Manny's best hope is that he can throw a lot of shots and use his greater work-rate to take a decision. The judges seem to have soured on Floyd recently, though, as some ridiculous cards have popped up in recent fights. If things go the way they should go, Mayweather will lose a couple of early rounds then take a clear decision or stop Manny with body shots. People are making a big deal about the southpaw issue. Yes, Mayweather has had moments where he's struggled with portsiders. On the other hand, he's had many more moments in fights where he's dominated them. He should be able to decode Manny quite quickly.
 
James Goyder (Mayweather UD): At the risk of stating the obvious... Mayweather by unanimous decision. Hope I'm wrong.

David Greisman (Mayweather Dec.): Yes, this fight is coming years after it should've. But it's still pitting two of the best fighters in the sport today against each other. It's still an incredibly intriguing pairing, one that I can see going in so many different ways, but one that I must still pick with Floyd Mayweather as the winner. Mayweather remains so adept at making his opponents miss, taking away their opportunities, then picking them apart with precision. Yes, he is slowing down a bit and did take more from Marcos Maidana than we're used to seeing. And yes, he's not faced anyone like Manny Pacquiao before, whose feints and movement and speed can give even great boxers trouble. I can see the possibility of Pacquiao catching Mayweather. But in the end, I remember what defensive or mobile boxers have done to Pacquiao's style in the past. He's held back at times, wary because of the possibility of what may return, content to box more wisely. He triumphed in nearly all of those fights. Yet Mayweather is better than them. He remains the best in the sport for a reason. Mayweather by decision, unless he catches Pacquiao with a perfect counter.

Peter Lim (Mayweather controversial UD): Mayweather hits the deck courtesy of a right hook and falls behind early in the fight. But he never makes the same mistake twice and gradually figures Pacquiao out to gain control of the middle rounds, deploying his masterful tuck-roll-and-counter maneuvers. Pacquiao comes on strong in the late rounds and sporadically rocks Mayweather with clean shots but Mayweather effectively kills his rhythm by smothering him before he can inflict further damage. After 12 suspenseful rounds, both the media and public are deadlocked. The rounds Pacquaio wins are decisive while Mayweather appears to have barely squeaked by more rounds. Since the 10-point must system applies, Mayweather's hand is raised by scores in the 114-113 to 115-112 range.

John A. MacDonald (Mayweather Dec.): Pacquiao will cause Mayweather issues in the early stages through his use of angles. By the the mid stages of the fight Floyd will have made the necessary adjustments to counter the Filipinos attacks. Mayweather to take a relatively close but fair decision

Takahiro Onaga (Mayweather UD): Manny will be made to look like an old man by Mayweather.

Per-Ake Persson (Pacquiao Dec.): Heart says Pacman, mind Mayweather but Pacquiao´s workrate and pressure could prove to be too much for Mayweather.

Cliff Rold (Mayweather Dec.): My anticipation is growing and I can see ways Pacquiao can win. I just think Floyd WILL win. Both men have slowed down from their peak and that favors the more technically sound Mayweather. This could be a lot of fun in spots but Mayweather has had the better chin; a knockout for Pacquiao isn't a safe bet. In order to pick Pacquiao, it has to be assumed he can win enough rounds to score a decision. It's not far fetched, but going with the most likely scenario.

Franisco Salazar (Draw): I don't see where writers and boxing people believe Mayweather will KO Pacquiao. Mayweather has always had problems with his hands. Roach will not just have any game-plan. If he can get Pacquiao to back up Mayweather, attack the body by going in and out, and peppering Mayweather with a jab, Pacquiao has a chance. IMO, Pacquiao will be the one who moves around the ring more, while Mayweather will try to look for the straight right hand. Wouldn't be surprised if someone scores a flash knockdown.

Victor Salazar (Mayweather Dec.): I should pull a Miguel Cotto and not make a pick because I’m honestly not confident in either pick. Initially I felt Mayweather would win by decision as I always have. Then with the additions of Ariza and the physique Mayweather has shown, I thought Mayweather by knockout. Still in the back of my mind I can’t help but think Marcos Maidana landed on Mayweather and so did Miguel Cotto, two fighters who aren’t as fast and don’t possess the footwork of Manny Pacquiao. Also, the left jab was key in both Cotto and Maidana’s success. As De La Hoya said on HBO, the straight left will be key for Manny Pacquiao along with his activity. That being said, it’s hard to pick against Mayweather. I will root for a good fight and if the there is a decision, I hope the right man wins as the world will be watching.

Reynaldo Sanchez (Mayweather UD): If this fight may be real, I should say that this is a 50-50 fight. However, when one side keeps everything in its favor. We can say that this is a typical fight conducted in a controlled environment. In my opinion, Las Vegas, Bayless and judges, will be the factor to determine the winner. Logic says that Mayweather should win and that is what you will see after 12 boring rounds.

Alexey Sukachev (Mayweather MD): Not much to comment. I expect a really fiery fight - thanks to Manny's determination and fight style. He isn't considerably worse than he was at his peak. Still, mastery of Mayweather and his skill set will frustrate the Filipino with Maywaether getting an edge in a close fight.

Stacey Verbeek (Pacquaio SD/MD): Going with the underdog, Pacquiao on this one. Pac will use darting speed and power to chip away at the Mayweather defense and rack up points early on. I would not be surprised to see him controversially drop Floyd early and it get attributed to a slip or stepping on a foot.  Mayweather will shake it off to take rounds, bringing it close, but Pacquiao will win on a SD or MD..... and then extend to Mayweather a rematch offer in the Cowboys’ AT&T Stadium in Arlington, TX.

Danny Winterbottom (Mayweather UD): With his southpaw stance and blistering attacks, Pacquiao will cause Floyd problems in the early going until the Las Vegas resident begins to find his range with sharp counter punches. Manny will push him close but I feel Floyd will pull away in the final third for a unanimous decision victory or even a late stoppage if he feels Pacquiao is there for the taking. In a fight of this magnitude Floyd's ego may over take his safety first approach and we could see an exciting finish to an absorbing, tension filled affair.

Totals:
Mayweather–11
Pacquiao–4
Draw–1

Jake Donovan is the Managing Editor of BoxingScene.com. Twitter: @JakeNDaBox