Zac Efron, Adrian Grenier

Vince, Ari and the Entourage crew will have another Hollywood ingénue to pal around with this summer: Zac Efron is joining the posse.

The High School Musical star is set to guest on the HBO series, according to E! A source says that Efron was filming scenes for the show at Beverly Hills Niketown Tuesday morning.

"He was filming a scene and talking on his cell phone," the source said. "None of the other Entourage cast was [there]. He was really nice."

Details on Efron's role are yet to be announced, but he joins a healthy roster of boldfaced names set to appear as themselves during Season 6, including Lil Wayne, LeBron James, Tom Brady and Aaron Sorkin.

A rep for the show did not immediately respond to TVGuide.com's request for comment.

Would you tune in to see the tween hunk?

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