A oouple of years ago, Joss Stone opened for the John Mayer Trio and was SO MUCH BETTER, that even John Mayer stated that "they should have opened for her." This was at the Fillmore in Denver.
'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.