Jonas Brothers at Arthur Ashe Kids Days -- VIDEOS!

Big Rob joins in on the fun with the Jonas Brothers as they perform on stage at the 2010 Arthur Ashe Kids Day held at the USTA Billie Jean King National Tennis Center in New York City on Saturday afternoon (August 28).

Joined by Demi Lovato, David Archuleta and Allstar Weekend, the musical trio hit up some of their favorite tunes during the concert.

The day before, Kevin, Joe and Nick won yet another Road Dogs baseball game. Check out the video!

10+ pics inside…