'they blew'em off the stage'

1973 Paramount Theater, Portland: Little Feat (the Lowell George band), with the-then traditional finale of "Tripe Face Boogie", leaving an obviously compromised Sly Stone nothing to do but shuffle around for 35 minutes and go home.

John Legend thoroughly outperformed Alicia Keys at a performance at the Kodak Theater in LA several years back.

Ten Years After opening for Peter Frampton.
My memory is a little less clear on this, you know the times were different then, but I seem to recall King Crimson opening for Golden Earing.
I wasn't there, but, it's been reported that Jimmy Hendrix opened for the Monkeys.

Jay Ferguson, ex of Spirit, blew the Doobies off the stage on a nightly basis in support of his Thunder Island album. I used to work for Jay as his lighting designer. He had a remarkably tight band and he was a one man wrecking crew on stage. The press coverage started to become embarassing for the Doobie Brothers so we came off their tour and started headlining our own in smaller venues.

In 1987 I was in the front row when The Cult opened for Billy Idol.

Idol was pretty good, but The Cult just brought the house down.