Rihanna -- Pulls Hat Trick with Karim Benzema ... 3rd Late Night Together

For the 2nd time this week, Rihanna and soccer star Karim Benzema hit the SAME L.A. nightclub ... after hanging together in NYC ... so, is this thing official yet or what?

RiRi and and the Real Madrid star hit up 1 OAK on the Sunset Strip ... and just like the last time they partied together, they left separately and went in separate cars.

But here's what we do know ... the two first started chatting last year during the world cup via Twitter. And earlier this month, they met up at a cafe in NYC for a super late night snack.

Then the party shifted to the West Coast ... they clubbed together on Monday night and Karim bought a bouquet of flowers on the way out.

We tried asking Karim what the deal is with Rihanna on his way out of 1 OAK but his lips were sealed.

So ... item? Or not an item?