Look out Pam -- John Krasinski has a new leading lady!

The "Office" actor has been quietly dating Brit beauty Emily Blunt -- but at the SAG Awards, both Emily and John played coy about their relationship!

When asked about the "Devil Wears Prada" star, Krasinski said, "I don't talk about that." We also asked Blunt about her relationship with John, to which she replied, "No idea -- never heard of him."

The two were later spotted cozying up at the afterparty! "They were very cute to each other," People magazine's Jen Garcia tells us.