The best opening act you've ever seen & heard?

I have two:

In 1983 I went to see The Plimsouls (Peter Case’s pre-solo career band) at The Garage, a tiny little "club" on Ventura Blvd. The room had filled up (elbow-to-elbow tight), and the opening act started their set. My woman and I both looked at each other, our mouths agape. It was Los Lobos, and they were great! Their debut album How Will The Wolf Survive? had yet to be released, but I sure picked it up when it was.

I went to see John Hiatt at The Roxy Theater on Sunset Blvd. during his Perfectly Good Guitar tour, entering the room just as the opening act was starting her final song. The ads for the show listed her name, which was unfamiliar to me. As the song started and progressed, I was stunned; the song she and her band were performing was a great one, and I knew I had missed a quality set of music. It was Sheryl Crow, whose debut album had not yet been released. Damn it!