Floyd Mayweather is teaching Justin Bieber to box -- seriously

The best pound-for-pound boxer in the world is apparently teaching one of the biggest pop stars how to box. Because, why not?

Both Floyd Mayweather Jr. and Justin Bieber posted pictures and video to social media Thursday night of the "Biebs" getting lessons from "Money Mayweather."

Bieber, decked out in full boxing attire, was shown working in the ring with the undefeated Mayweather, who was wearing pads on his hands for Bieber to hit.

Mayweather even gave Bieber a new boxing nickname, "Money bags."

It is unclear how long the two have been training together, but they have been close for years and are often spotted hanging out together.

Bieber is usually seen in attendance at Mayweather's fights.

What's more, the two are both major investors in the social media tool, "Shots," which is what the boxing pictures were posted on originally.

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UPDATES

3:27 p.m.: This story has been updated with information that both Bieber and Mayweather are investors in the social media tool they used to post the pictures.

This story was originally published at 5 a.m.