One win from their last nine league games leaves Everton just five points above the bottom three.
But there were positives to take from Thursday's 4-1 UEFA Europa League win over Young Boys, with Romelu Lukaku scoring a hat-trick ahead of the weekend's match against the division's bottom club.
"Our group is looking stronger game by game and experiences that we had already will help us to face a strong Leicester side," Martinez said.
"We know how difficult they're going to be.
"They've been very competitive. I don't think their points tally is a true reflection of what they've done and it's going to be difficult.
"We can't look at the table, nothing is a given. If anything you need to be perfect with your performance."
Everton have drawn their last four games at Goodison Park and were also held 2-2 by Leicester when the sides met on the opening day of the season.
After a promising start to the campaign, the 13-match winless run that followed has left Nigel Pearson's side constantly playing catch-up, while defeats in each of their last four league outings leaves them five points from safety with time running out.
"All games are big now and we must find ways to win," said the City boss. "Performances must warrant the support of our fans
"Key games are against those near us, but every game is an opportunity. We need consistency in our performance. Results must improve."
