Sammy Hagar receives a little surprise

"I can't believe you're here," said Hagar to Kenny Chesney. "You missed my birthday party, but you showed up for this... Alright!"

The two hugged and laughed, and then Hagar, dressed in long patch madras surfer baggies and red athletic shoes, instructed his jagged four-piece into I'll Fall In Love Again. Hagar gave his friend and let him take the first verse - and it wasn't long until the pair was holding their microphones out to the crowd.

"When someone like Sammy decides to play a song like that - and looks at you to take the first verse," Chesney said upon leaving the stage, "well, that's heavy. But then, that's Sammy, you know? He's the kind of guy who throws it down so hard, but never loses sight of why it matters... And it made me glad that in the middle of all this 3-D movie stuff, I was able to get free for a couple days to go to Morgan's premiere, then get over to Vegas to see my buddy for something as cool as him opening his new Cabo Wabo."

In the thick of editing 3D footage captured at several of this summer's NFL Stadium shows, Chesney took a little break to get out and spend some time with his friends: first attending Morgan Freeman's "Invictus" movie premiere in Beverly Hills, then heading to Las Vegas.

"It's a crazy life," he said. "You know, to be in Nashville looking at footage, then in California to see an amazing film with one of my favorite people, then off to Vegas to blow it up on a tiny little stage with one of the most intense rockers I know... How this happened I don't know? But I like the fact that I can take a few moments and share it with my friends."