Boxing legend Roy Jones Jr. says he'll GLADLY accept Vitor Belfort's challenge -- telling TMZ Sports he's down to brawl with the ex-UFC champ ... but needs 6 weeks to prepare.
Just last week, 41-year-old Belfort -- the former UFC lightweight champ -- called out Roy during a media event for the ONE Championship MMA promotion.
"One fight I'd really love is me against Roy Jones Jr. Roy, wherever you are, I wanna come challenge you for a boxing match, but with this condition: I'm gonna be able to dirty box with you.