Zac Efron is a Basketball Balla

Zac Efron sports his famed top-knot ponytail again during basketball practice at the First Hollywood Presbyterian Church in Hollywood on Tuesday.

Why the sudden interest in basketball?

The High School Musical star is probably improving his basketball skills for his role in the upcoming film Seventeen.

Air Zac will star as the 17-year-old version of an adult who is zapped into a younger body.

20+ pictures inside of Zac the basketball balla…