After beating Cameroon 4-0, Croatia maintained their hopes of making the knockout stages, but they know they will need victory in their final game to secure progression.
"The match against Mexico will be like a final. We have to get some rest, because a serious opponent awaits," he said.
"Mexico are strong, but so are we. The Mexico players are very patriotic, just like us, and they have a great team spirit.
"They play some aggressive football with a lot of pressing. They are strong going forward, but also have some weaknesses in defence, like Brazil showed us."
Kovac was pleased with how his side performed against Cameroon.
"We weren't on top of our game in the opening five to 10 minutes and Cameroon created some chances," he said.
"But then we found our rhythm. Olic scored and that opened up the game for us. We could have scored even more goals.
"I can only congratulate the players, though. They won in very difficult conditions. It was hard to sit or stand, let alone run around on the pitch."