Greg Hardy: I'm Down for the XFL, If They Pay Me Right!

This could be very interesting for Vince McMahon ... ex-NFL star Greg Hardy says he'd be down to join his XFL league if the WWE honcho really does bring it back.

Of course, 29-year-old Hardy is currently fighting his way into a pro MMA career (he's already 2-0) -- but tells TMZ Sports he still loves the game of football and would be open to giving it another go.

"If I get paid ... I'd probably be there, man."

Meanwhile, Hardy says he's still VERY focused on climbing the ladder in MMA -- and ultimately has his sights set on fighting in the UFC so he can compete against the best in the world.