Here's a great sounding clip of Elvis doing his signature opener, a jazzed-up rendition of 1924's oft-covered C.C. Rider.

The intro alone is worth a watch, with backstage footage showing an intense Elvis mopping his brow and making his way to the stage with his handlers. I think this comment from YouTube sums it up best...

Whenever I watch Elvis getting ready to go on stage, like in the first minute of this video, it is like watching an airplane getting ready and waiting on the runway for takeoff, all that energy, just raring to go.
— iluvlvis

You can find this clip and more on Through My Eyes, a 3+ hour documentary that's basically an improved rebuild of the already fascinating Elvis on Tour (1972).

Thanks to rizzy26 for posting the video.