Jake Paul's pulling out all the stops for his big return to the ring ... and the footage from his training sesh with boxing legend "Sugar" Shane Mosley is INTENSE.
Of course, Paul's fighting fellow YouTube superstar AnEsonGib during a Super Bowl week extravaganza ... and JP's been training like an animal at Mosley's gym in Big Bear.
The footage -- part of DAZN's 40 Days doc -- is pretty impressive ... and despite Paul wanting to avenge his brothers loss and take on KSI, it's clear he's laser focused for the January 30th fight.