Soundgarden made Guns-n-Roses look and sound like amateur night.
'they blew'em off the stage'
what concerts have you attended, where the warm up act blew the headliners away.....my examples...brownville station upstaging zz top to the point where people where chanting 'brownsville station!' during the littl ol' band from texas' set.....another..t.rex upstaging lynyrd skynyrd(yes there really was such a show), and the grass roots upstaging cream.