ET is with Renée Zellweger and Harry Connick, Jr. -- and we've got the details behind why the co-stars loved working together in their new romantic comedy 'New in Town.'

"The thing about Renée is, if you don't have chemistry with her, then you have the issue ... because she is so giving, so gracious, and such a talent that it was so easy to have a relationship with her on screen as well as off," Harry tells ET about working with Renée.

'New in Town' follows Lucy Hill (Renée Zellweger), a successful Miami-based executive, who is sent out of town on a temporary assignment that will surely get her recognized and promoted. But Hill ends up meeting the man of her dreams (Harry Connick, Jr.).

Renée and Harry's new film hits theaters on January 30.