Pacquiao (58-6-2, 38 KOs) is boxing's only eight-division world titleholder and has had several memorable fights during his 21-year career, including four incredible battles with rival Juan Manuel Marquez.

Here's a look a list of some of Pacquiao's biggest and more important moments throughout his career:

Pacquiao vs. Oscar De La Hoya

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Pacquiao moved up to welterweight to face Oscar De La Hoya on Dec. 6, 2008, in one of the biggest fights in boxing at the time. Pacquiao scored a huge upset with an eighth-round knockout of De La Hoya, who then retired.

Pacquiao vs. Miguel Cotto

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On Nov. 14, 2009, Pacquiao stopped Cotto in impressive fashion to take a welterweight world title and win a title in a record-setting seventh weight class.

Pacquiao vs. Marco Antonio Barrera I

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Pacquiao's first big victory came on Nov. 15, 2003, as he shredded Barrera in an 11th-round knockout win to claim the lineal featherweight championship.

Pacquiao vs. Antonio Margarito

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On Nov. 13, 2010, Pacquiao dominated Margarito in a decision win to claim a vacant junior middleweight title and extend his record by winning a world title in an eighth weight class.

Pacquiao vs. Ricky Hatton

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A fight -- and a stoppage -- to remember. On May 2, 2009, Pacquiao dropped Hatton twice in the first round and then flattened him in the second to win a lineal junior welterweight title.

Pacquiao vs. Floyd Mayweather

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It wasn't a win in the ring, but it was successful financially for Pacquiao. On May 2, 2015, the Pacman lost a decision in a welterweight unification fight against Mayweather in the richest fight in boxing history. Pacquiao earned around $150 million.

Pacquiao vs. Erik Morales II

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On Jan. 21, 2006, Pacquiao knocked out Morales in the 10th round in the second of their three fights to avenge a decision loss the previous year. Pacquiao went on to defeat Morales in their third fight three months later.

Pacquiao vs. Juan Manuel Marquez III

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In another extremely close fight, Pacquiao won a majority decision over Marquez on Nov. 12, 2011, this time to retain welterweight title in their third meeting.

Pacquiao vs. Marquez II

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On March 15, 2008, Pacquiao scored a split decision win over Marquez in their second fight to win junior lightweight title.

Pacquiao vs. Lehlo Ledwaba

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In his first fight in the United States and first with trainer Freddie Roach, Pacquiao burst on the scene with a sixth-round knockout of Ledwaba to win a junior featherweight title on June 23, 2001, in Las Vegas.

Pacquiao vs. David Diaz

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Pacquiao moved up to lightweight and stopped Diaz at 2:24 minutes of the ninth round to win a lightweight title on June 28, 2008. At the time of the stoppage, Pacquiao was winning on all three judges' scorecards, 80-71,80-72 and 80-71.