The teams clash on Saturday at Goodison Park with the Hammers in fourth with 18 points, six places ahead of the Toffees.
And Martinez said: “West Ham have been the most consistent team in the Premier League and it isn’t by accident.
“The way they play is very brave – they’ve a lot of attackers. It’ll be one of our the biggest challenges.”
He added: “It is still early days but we still have four teams challenging for the title and eight teams looking for Europe.”
“West Ham are one of the big challengers for those places without a doubt.”
There are currently four points separating West Ham and Tottenham in 12th.”