We didn't see this coming!

John Mayer has his claws on another famous lady -- this time it's Demi Lovato! The serial celebrity dater has been out of the spotlight for a while but this will certainly put him back in it! The rocker, 39, and the pop star, 24, dined together at Hollywood hotspot Catch, on Saturday, arriving separately and departing separately, but they got cozy at the rooftop restaurant according to an Us Weekly source:

"John had his arm around Demi and was whispering sweet nothings into her ear. She was into it. They weren't making out or anything, but she was giggling the whole time." Another source tells the mag the couple "chatted it up for over an hour," and said Mayer gushed over Lovato, saying she "has one of the greatest voices."

Demi has dyed her hair back to brunette, which she showed off against a leopard-print jacket, while Mayer had an eclectic look -- a Hawaiian-print shirt with jeans.

This isn't the first Lovato-Mayer intersection; the two collaborated on the 2013 single "Heart Attack." Of that experience, Lovato told MTV News, "The process of the collaboration was actually really funny because he's a really, really funny guy, and he talks a lot, so he'll go off on something. ... I had a great time. He taught me a lot about the business and gave me a lot of advice."

Mayer previously dated Katy Perry, Jessica Simpson, Taylor Swift and Jennifer Aniston, while Lovato is recently split from Wilmer Valderrama.