The goalkeeper has established himself among the top shot-stoppers in the Premier League since arriving from the Emirates just over a year ago.
Martinez is also now Argentina’s No.1, helping his nation end their long wait for major tournament success in last summer’s Copa America. The 29-year-old was this week hailed by international team-mate Lionel Messi as “one of the best goalkeepers on the planet” following his heroics in the most recent World Cup qualifiers.
Martinez did not concede a goal in three matches during the international break and Smith said: “The confidence Emi’s built since he came here has been excellent. I think everybody knows what Lionel Messi thinks of him.
“Messi had been trying to win a major tournament for a long period and Emi was a big part of why Argentina went and won the Copa America. He’s held in high esteem by Messi and all the Argentinians.
“He is looking a bargain at the moment but we knew we were getting a good goalkeeper.
“I think he’s probably surpassed all our expectations of what we thought he would and he’s growing in confidence every game, which is obviously good for us.
“We were thankful we managed to get Emi in and he’s proved what a good goalkeeper he is.”