Benitez told liverpoolfc.tv: "Pepe will remember this mistake as important, so for him it was a test and he showed that he can come through difficult situations and be really good.
"If you are always playing well and without difficulties you cannot test the character of the player.
"Pepe made some mistakes but after this he showed quality and character.
"Also, you can see when he has been under pressure in finals and other big games that he is a player with a very good mentality."
Benitez claims he knew Reina could be a world-beater from the moment he set eyes on the youngster playing for Barcelona. He even wanted to sign him back in 2001.
"We were looking for a new keeper and we were playing a tournament in Lanzarote which Barcelona were also involved in. On this occasion Pepe was going through his warm-up with Victor Valdes and I was stood behind him watching.