The Getafe stopper flew across to his right to keep out Messi's free kick which had looked destined for the top corner.
It looked for all the world as if Messi was about to equalise but Guaita's impressive stop denied him.
Messi's face was a picture.
Check out the save for yourself below:
No hay muchos porteros en el mundo que dejen a Messi con esta cara. Guaita lo ha hecho...PARADÓN pic.twitter.com/9Sel9np8lI
— Carlos Muñoz (@CarlosMdelReal) 16 de septiembre de 2017