pop star singer filming friends with benefirs suit Justin Timberlake Mila Kunis

But only as the cameras roll!

Now that Jessica Biel is in town, we're guessing Justin Timberlake is going to have an extra set of eyes watching him as he shoots Friends With Benefits in NYC. Not that Jess has anything to worry about with Mila Kunis -- we're pretty sure that JT and the brunette beauty are keeping it strictly professional...