Watch it all.
Apart from the jaw-dropping speed, and beating the defenders, what always impresses me about this kind of goal is the split-second timing: there is the tiniest window, a second or so to blast the ball through the narrowest of gaps. It must take incredible alertness to be able to do this.
I saw this live and am still not over it. What’s amazing about the video is that the actual play is longer, Messi gets the ball originally not far from midfield.