If Neymar suddenly gets the urge to get a little gambling in -- all the guy's gotta do is look down at his wrist ... 'cause the soccer superstar just copped a "Casino" watch that features a moving, built-in roulette table!!
TMZ Sports has learned he recently snagged the piece from Jacob & Co. ... and it's awesome -- and quite pricey.
We're told it's worth $280,000 ... but well worth the cost -- as it comes with all kinds of bells and whistles.