Joe Jonas Heavyweight Hunk

9/14/2016 11:37 AM PDT

Joe Jonas is a Heavyweight Hunk

Joe Jonas looks like he's shaping up to be a fine fighter ... emphasis on fine.

We got Jonas Bro #2 out in Bev Hills where he was practicing his hook and uppercut against women's boxing champ Ava Knight, showing off his sculpted bod in the process.

He's been training hard lately, and so has Nick. So we gotta ask ...