Pop sensation Justin Bieber is a longtime acquaintance of undefeated boxing legend Floyd Mayweather Jr. With that in mind, a video of the musician hitting the pads with the boxing star has made its way to the internet. Justin Bieber has shown a great interest in boxing throughout his career. Friends with "Money" Mayweather, the pop sensation recently stopped by Mayweather's gym for a little training. Watch Bieber hit the pads and hone his striking skills within the video provided above. For more MMA news click here.