From Fergie to Ozzy, Chicago-native Tim "Grape" Mattefs has traveled the world as a touring live concert technician. But the lifelong Chicago Cubs fan has never experienced a live performance at Wrigley Field, until now. In the midst of a massive world tour with Australian rock and roll giants AC/DC, Mattefs will take the field of the "friendly confines" on Tuesday for a sold-out rock show of the ages.