Now THAT'S an odd couple!

Rihanna went on a date with Rob Kardashian Saturday night -- and though it started with a pretty innocuous trip to Racer's Edge Indoor Karting in Burbank, it ended at Playhouse nightclub in Hollywood!

Just a week after Rihanna's self-expose on Oprah's Next Chapter, in which the singer said she still loves Chris Brown despite his arrest for physically assaulting her in 2009, RiRi stepped out with the least famous Kardashian.

This isn't Rob's first foray into dating hot pop stars ... the reality show star was dating UK's Rita Ora not too long ago and even went on a double date with his honey and sister Kim Kardashian and her beau Kanye West in May.

You think Rob and Rihanna could last or will Ri race away from Rob as fast as you can say Chris Brown?