Warner was a late replacement for No1 Antti Niemi and Sanchez said: "I've got to say that Tony Warner was excellent.
"It's a very difficult position being a number two goalkeeper in the Premiership. You need to have the quality so you can play but you also need an ego that allows you to train and work hard in the knowledge that you're in the shadow of someone else.
"Tony does that with a smile on his face, he's a great character to have around and I was very pleased that when he came in, he did himself justice. He kept us in the game and to be beaten by a penalty and end up on the losing side is very harsh on him.
"There were a lot of positives to take out of the game but there are lots of things we need to improve on and conceding two goals with eight minutes to go is something we need to work on."