Pacquiao is boxing's only eight-weight world champion
Manny Pacquiao is due to step into the ring against WBO welterweight champion Jessie Vargas in Las Vegas on Saturday.
The Filipino icon has won a record eight world titles in different weight classes and is coming off a unanimous decision victory over Timothy Bradley.
Pacquiao enters the ring with a record of 56-6-2 with 38 wins by way of knock-out. Vargas holds a 27-1 record and will be making the first defence of his title.
We look at the Filipino legend's five most exciting bouts:
5. Juan Manuel Marquez 4 - 8th December 2012
Pacquiao squared off against his greatest rival for a fourth time. Their three previous bouts had ended in a draw and two razor-thin Pacquiao decision victories. Going into the bout, both men had promised to win by KO and that's what we got.
Pacquiao started the brighter but got sloppy and Marquez put him on the floor for the first time in their rivalry in the third round. The knockdown only seemed to enrage the 'Pacman' who came roaring back and evened-up the knockdown count when he put the Mexican down in the fifth.
Pacquiao picked up where he left off in the sixth and Marquez looked like he was done. His nose was broken and he had been getting hit by power shots repeatedly before he landed one of boxing's most memorable punches.
With seconds remaining in the sixth, Pacquiao came thundering towards him only for Marquez to finally read the Filipino's feint and land the perfect counter-right hand punch leaving Pacquiao motionless on the canvass.
Pacquaio chased the Mexican for a fifth bout but Marquez has refused to allow him any shot at redemption.
4. Ricky Hatton - 2nd May 2009
The Filipino was coming off an impressive win against Oscar De La Hoya before taking on the popular Hatton.
Hatton, who was unbeaten at light-welterweight at the time, was coming off wins over Juan Lazcano and Paulie Malignaggi before stepping in against Pacquiao.
The bout was a brief affair as Pacquiao's speed was too much for the Briton. Hatton was down twice in the first and barely made it to his stool at the end of the round.
It appeared Hatton's strategy was to block punches with his head but the end came with only seconds remaining in the second round.
Pacquiao loaded up on a huge left hook which landed plum on Hatton's chin and left him flattened out on the canvas.
3. Oscar De La Hoya - 6th December 2008
Pacquiao faced arguably his biggest challenge when facing the former Olympic champion. He had never fought above 135 lbs and was due to face the Mexican-American at the 147 lbs welterweight limit. Many feared for the safety of the minute Asian but they were worried about the wrong fighter.
De La Hoya hadn't made the welterweight limit in 7 years and by the time of the bout, the weight cut had taken its toll on him.
Pacquiao was too fast and too smart for De La Hoya as he would land countless straight left shots before pivoting away from danger. Essentially, the Filipino turned the great American legend into a punchbag.
By the end of the 8th round, De La Hoya had had enough and stayed on his stool. He retired after the fight having only been stopped twice in his career.
2. Miguel Cotto - 14th November 2009
By the time he stepped into the ring to face Cotto, Pacquiao was on a tear. He hadn't lost in 10 fights and had avenged his loss against Erik Morales with two TKO wins against the Mexican great.
His win against De La Hoya was a surprise to many but most observers figured a prime Miguel Cotto would surely be too much for the diminutive slugger.
Instead, the 'Pacman' treated fans to one of his finest performances. He weathered an early Cotto onslaught before knocking him down in the third and fourth rounds.
The Puerto Rican fought on bravely but the writing was on the wall as he was hunted down mercilessly. Referee Kenny Bayless called a halt to the action in the 12th round after seeing one power punch too many land on Cotto's chin.
1. Juan Manuel Marquez 2 - 15th March 2008
The second bout of the Pacquiao/Marquez rivalry had all the ingredients of the classic "aggressive fighter versus counter-puncher" style fight.
Pacquaio flew in whenever he could while Marquez waited for him. Marquez started the brighter, buzzing the Filipino in the second. Pacquiao came roaring back and knocked the Mexican down in the third.
The fight ebbed and flowed for the full twelve rounds with Pacquiao winning a split decision from the judges.