Ajax went into the mid-season break top of the table, ahead of Vitesse on goal difference, and De Boer knows that his team will have to be at their best if they are to start the second half of the campaign well.
Sunday's opponents PSV have struggled under Phillip Cocu, with only seven wins from their 18 league fixtures, leaving them in seventh position.
One win in 12 games from October to mid-December piled the pressure on Cocu, but two successive victories prior to the mid-season break means that PSV are a real danger, according to De Boer.
"It will be a tough match against PSV," he said. "But I'm glad we're going to start again.
"We have to play against everyone once. We just have to be awake.
"I don't look back, but forward to the next game.
"This position (being top) will not result in pressure along with it. Whether we are first or second, we just have to play our own game.''
