Chace Crawford & Bar Refaeli Couple Up -- JustJared.com Exclusive

Chace Crawford and Bar Refaeli are starting to get friendly with each other.

The Gossip Girl hunk and Sports Illustrated cover model, both 24, shared a special moment on Friday night (September 11) at NYC hotspot 1Oak.

During Jay-Z‘s “Run This Town,” they were “dancing on each other, swaying their hips together from side to side,” a partygoer exclusively tells JustJared.com. “At one point, Bar reached down and grabbed Chace‘s backside. They were very affectionate with each other.”

Another source reveals, “Bar and Chace have been spending a lot of time together since Bar is town and attending NY Fashion Week events.” (During Fashion’s Night Out on Thursday, Chace dropped by the Dolce & Gabbana boutique while Bar was at the Ralph Lauren boutique.)

Spotted at the booth next to the unlikely pair: Rihanna hanging out with her entourage. Jay-Z and Kanye also dropped by the club, celebrating their performance together from earlier in the evening at Jay-Z‘s 9/11 benefit concert.

Last month, Chace was seen kissing Twilight cutie Ashley Greene. Bar called it quits with Leonardo DiCaprio back in June and has been linked to Brazilian polo player and entrepreneur Ricardo Mansur.