Here's Serena Williams getting boxing lessons from one of the fiercest fighters of all time ... and Mike Tyson's showing another champ how to throw a serious haymaker!!!
Check out this video of Iron Mike working with the tennis star in Florida ... coaching her through some punching combinations and then holding the heavy bag as Serena absolutely unloads.
Sounds like Mike is impressed with Serena's punching prowess ... Tyson says she "has some serious power." Talk about a ringing endorsement!!!
No word if Serena can take a punch like Mike ... but she can sure as hell throw one!!!