Zac Efron is set to challenge Adrian Grenier for the title of top TV hunk - the teen heart-throb is to join the cast of ENTOURAGE.
The High School Musical star filmed a cameo appearance for the hit HBO show at a Beverly Hills shoe store on Tuesday (02Jun09).
A source tells E! Online, "He was filming a scene and talking on his cell phone. None of the other Entourage cast was here. He was really nice."
The sixth season of Entourage will see Grenier line up against a string of celebrity guests including rapper Lil Wayne and supermodel Gisele Bundchen's sports star husband Tom Brady.
The series begins in the U.S. on 12 July (09).