Hollywood hunks Zac Efron and Robert Pattinson are best buddies now.

Efron, 26, and Pattinson, 28, were spotted partying late night at a West Hollywood Bootsy Bellows. They were joined by the House Bunny actor Ryan Rottman, reported Us Weekly.

And, this was not their first night-out together!

The Neighbours actor and the Twilight star also visited the Hollywood's Chateau Marmont last Friday.

"They went there super late to try to avoid any crowd," the source said.

Apparently Efron's rumoured girlfriend Michelle Rodriguez hung out with the pair before she and Efron left for her house, the source added.

The two have become good friends and have been spending evenings out on the town together in recent weeks.

According to the source, "Zac has gotten to know Rob more and more through mutual friends and they enjoy talking about what they're working on in the future."

"Zac really likes the movies that Rob is doing right now and Rob has so many questions about growing up in Hollywood like Zac did. They seem to really click."

In addition to their party time at Bootsy Bellows, Efron and Pattinson were also seen mingling outside of the Pinz Bowling Center in Studio City on Tuesday.