Ezri Konsa's goal was enough for the 1-0 win but Villa's success wars largely down to Martinez's super stop to deny John Lundstram's penalty just before half-time.
"He didn't have an awful lot to do," Smith said of his classy Argentinian. "His distribution is really good. He's calm, assured. He's got a really good personality.
"To keep a clean sheet and to save a penalty in your first game... I've not seen it back, it looked harsh at the time.
"He's had to go and make a good save and he's done that."