Ex-NBA Star Deron Williams Added To Paul-Fury Undercard, Could Fight Frank Gore

The Jake Paul vs. Tommy Fury fight just got a helluva lot more interesting -- ex-NBA star Deron Williams (yes, the dude who played for the Jazz) has been added to the undercard ... and he could be going up against none other than former NFL running back Frank Gore!!!

Williams -- the third overall pick to the Jazz in 2005 -- reportedly just signed on to follow in Nate Robinson's footsteps and make his boxing debut on December 18 in Tampa Bay.

While Williams doesn't have any fights under his belt, we're told he's actually nothing to scoff at -- Deron was a state champion on the mats in Texas. He won titles as an 8 and 12-year-old in 1993 and 1997.

UFC fighter Ryan Spann -- who trains with Williams at Fortis MMA -- said he even sparred with the guy and got his ass beat!!!

As for his opponent, Shams Charania says it could be Gore -- a 5-time Pro Bowler who played 16 years in the NFL.

Gore has put in some serious training off the field and has shown he's got some skills, so it could end up being quite the interesting matchup.