Matt Barnes -- Hookin' Up With Rihanna ... A Real Possibility

2:55 PM PT -- Rihanna, clearly a TMZ Sports fan, just shot Matt down via Instagram.

Matt Barnes is confounding ... he says the stories about him going on dates with Rihanna are all gossip, but then he says things could be going down the relationship road.

We got Matt out at the UCLA Softball Stadium Saturday when he said he and RiRi are just friends, but it could lead to something. Interesting, because it sure seems like she's dating Lewis Hamilton.

He went as far as saying it doesn't matter that he plays for Memphis, because she has a jet.

Our sources say Matt and Rihanna were out on 2 dates fairly recently.