Zac Brown Surprises Billy Joel Fans at Fenway Concert [VIDEO]

Zac Brown Band played two legendary concerts at Boston's Fenway Park last weekend.  But Thursday night, Billy Joel played the historic venue.

For the encore, Billy Joel surprised his fans by bringing Zac Brown on stage to sing 'You May Be Right!'

Awesome!  The audio and video quality aren't the best in the video above, but you get the idea.