Karrueche Tran -- Miami Hangout ... with Manchester United Star

8:47 AM PT -- Sources connected to Karrueche tell us ... Memphis recognized Karrueche while hanging out at a club and asked for a photo.

We're told the whole exchange was friendly ... but they're definitely NOT dating.

She already kicked Chris Brown to the curb ... now, Karrueche Tran is kickin' it with an International soccer star ... and this guy is RICH!

Tran was hanging out in Miami with Memphis Depay -- a Dutch soccer superstar who plays for Manchester United.

In fact, the 21-year-old phenom just signed a reported $40 MILLION contract with Man U back in May -- so, dude's got money.

So far, no word if Karrueche and Memphis are friends ... more than friends ... or nothing at all.

But if there is something there ... upgrade?