Justin Bieber slated to perform at Summerfest in Milwaukee USA June 27, 2010

Usher and Justin Bieber may not be headlining but, they are among the biggest acts slated to appear during this year's massive Summerfest in Milwaukee.

Kicking off Thursday, June 24, Summerfest, as it has done for several years, brings both chart-topping and rising talent together for an over week long line up of performances making it one of music's premier summer festivals.

According to