The Toffees have been in front in both of their games so far this season but have drawn both 2-2 - against Leicester City and Arsenal.
Martinez admits those setbacks have hurt him and accepts that his players will have to be at their absolute best to take anything from the game against Jose Mourinho’s Premier League title favourites.
Martinez said: "We know it is going to be a difficult test, but we feel hurt about the points we have dropped so late and everything is down to us to try to be as good as we can,” he said.
"But unless you are at your top level you can't really compete against teams like Chelsea.
"It is clear Chelsea and Manchester City have started really strongly. They have shown they have no stopping period, they have just started where they left off.
"They are looking in top form straight away and it could be a really difficult sign for everyone else.
"We know how they played last season and now they have got more flair and more options in attack. That makes them a very complete team."
Martinez led Everton to fifth last season and is confident they can be a top side again this time around.
The Spaniard has been encouraged by some of his team’s play in their two games to date but is aware they need to maintain their good periods for longer.
Martinez said: "It has been very curious (so far). We have shown incredible signs of the team that we can be.
"We need to extend the first 45-minute performance for 90 minutes.
"When we do that I think we are going to see the potential of the squad."
Watch Everton take on Chelsea on Saturday from 4:45pm on Sky Sports 1 HD. Kick-off is at 5:30pm.