Check out this footage of the unemployed NFL star hitting the mitts in a boxing gym in footage AB posted on Tuesday.

The interesting part is the video was re-posted by DAZN, the live sports streaming service that carried the Logan Paul vs. KSI fight in November.

Paul already told us his camp had begun official talks with Antonio Brown to get a fight on the books -- and now it seems like DAZN could be seriously interested in getting a deal done.

As for his training, Brown's physique looks incredible but it's clear he needs real work in the ring to compete with Paul, who's already got 2 fights under his belt ... and looked pretty good in the KSI rematch.

Paul says he's dead serious about fighting AB and thinks it would be a great opportunity for the 31-year-old wideout to refocus his life while he's persona non grata in the NFL.

"I think we might be closer than anyone expects," Paul told us last week. "I'm f**king serious, bro. You know how serious I take fighting."