Martinez brought in Joel Robles from Wigan Athletic during the summer to provide competition for Howard, and the manager has shared his delight at his number one's response.
"Tim has been faultless since the start of the season," Martinez told the Liverpool Echo. "It is important in every position that you have good competition for places and have options.
"Joel Robles, who won the FA Cup last season, is going to bring that threat, but I thought Tim Howard showed on Saturday just what a magnificent moment of form he is enjoying. And what a magnificent goalkeeper he is.
"I can really say that I've not seen him do anything that has not been of the highest, highest level so I am really pleased in the competition we have in that position."
Everton host Tottenham Hotspur on Sunday in the Premier League.