Although Friedel may be 41 and supposedly in the twilight of his career, Guzan believes he is far from finished at the highest level.
Guzan, 28, said: "Brad keeps himself so fit, he helps the team get results and that's all you can ask for from your goalkeeper. His record speaks for itself.
"He's an extremely good professional when it comes to keeping himself sharp, ready and in shape. For him, age is just a number. You could never tell how old he is from his performances.
"What he is still doing at his age is remarkable and if you look at his form this season, he's been fantastic for Spurs. When that happens it's hard for the manager to make a change. Obviously, we spent quite some time together here at Villa.
"And to be honest, I had to be thick skinned and just keep myself ready - because as a keeper you never know when your chance will come.
"At times it was very frustrating but then that's part of being a goalkeeper. The situation with Lloris is something the Spurs manager will have to deal with."