Manny Pacquiao vs. Juan Manuel Márquez IV, billed as Fight of the Decade, was a professional boxing match. It was also billed unofficially as deciding the World Boxing Organization's "Champion of the Decade". This was the fourth and final meeting between Manny Pacquiao and Juan Manuel Marquez. The bout was held on December 8, 2012, at the MGM Grand in Las Vegas, Nevada and drew 1.15 million pay-per-view buys.

Marquez defeated Pacquiao by knockout with one second remaining in the sixth round. It was named Fight of the Year and Knockout of the Year by Ring Magazine, with round five garnering Round of the Year honors.