SPOILER Gossip Girl

Blair Waldorf (Leighton Meester) was spotted on more than one occasion with a new - and very good-looking - guy while spending time in the country this summer. The same guy was also spotted getting sweaty over a game of squash with Chuck Bass (Ed Westwick).

So who is this guy and what’s his story? Read on to find out.

The guy’s name is Marcus (Patrick Heusinger), a source close to the show tells PEOPLE.

“He’s Blair’s new love interest and Chuck’s rival,” the source says. “Blair met him in Europe, introduced by Ben, whom she flew to Italy with after Chuck stood her up.”

So what’s he doing playing squash with Chuck?

Observers at a recent New York City set, the Eastern Athletic Club on Clark Street in the Brooklyn Heights neighborhood, say Chuck may be taking a page from the Georgina Sparks (Michelle Trachtenberg) playbook by getting chummy with Marcus over a round of squash, earning his trust and then trying to screw things up for Blair. In the first season, Georgina secretly befriended Dan Humphrey (Penn Badgley) when she wanted to get back at Dan’s girlfriend, Serena van der Woodsen (Blake Lively).

At the end of the squash scene, observers say Marcus and Chuck shook hands on the court and then Marcus gave Chuck a number, which Chuck programmed into his phone.