The Notebook co-stars Rachel McAdams and Ryan Gosling have reportedly embarked on a hot new romance.

While the screen stars are remaining tight-lipped about their relationship, pals say they're just weeks into their relationship.

A source says, "They didn't have feeling when they worked together. And they haven't defined what they are because it's still so new."

Gosling, 24, previously enjoyed a brief romance with his 41-year-old MURDER BY NUMBERS co-star Sandra Bullock.

The couple thrilled the audience of the MTV Movie Awards in June (05) when they re-enacted one of their on-screen kisses from The Notebook on stage after winning the Best Kiss category.