Grass or clay? That's right – we're talking tennis! Tomorrow, the Jonas Brothers along with Demi Lovato, David Archuleta, Shontelle, and Nick Cannon will all be participating in Arthur Ashe Kids' Day (AAKD) – celebrating the ideals of humanitarianism and leadership through some games of tennis.

A portion of the proceeds from tomorrow's US Open event benefits the National Junior Tennis and Learning (NJTL) network, which promotes education through the development of family values and of course, tennis!

The JoBros and friends aren't the only ones jumping at this chance to do some good... tennis stars Rafael Nadal, Roger Federer, and Andy Roddick will be competing in some friendly matches too!