NBA's Glenn Robinson: Hey Stephen A. Smith ... Enough Talk, Let's Fight

Glenn "Big Dog" Robinson says he wants to end the beef with Stephen A. Smith once and for all -- IN THE CAGE -- challenging the reporter to a MMA match ... and he's dead serious.

The former NBA star joined the guys on the "TMZ Sports" TV show (airs tonight on FS1) -- to respond to an interview Smith did last week ... in which S.A.S. said he "despises" Robinson for being a hypocrite on race issues in the NBA.

Check out the teaser clip -- and make sure to watch the ENTIRE INTERVIEW tonight on FS1 ... it's intense!

Long story short ... Smith said Robinson always talked about helping black people succeed in non-player roles in the NBA ... but then trashed his former 76ers coach, Randy Ayers, who is black.

Robinson says Stephen A. is full of crap -- and says the real beef stems from a heated exchange in the locker room during his playing days.

Bottom line -- the 6'7" world class athlete says he's sick of talking ... and calls out 6'1" Mr. Smith.

Stay tuned ...