Mercedes boss Toto Wolff is wary of the favourites' tag being put on the Silver Arrows ahead of the Belgian Grand Prix.
Many are expecting Mercedes to get back to winning ways after the Hungaroring played to Ferrari's strengths before the summer break.
But Wolff said he is taking nothing for granted this weekend with Ferrari and Red Bull posing a threat.
"On paper, people will assume that Spa should suit our car because it is a circuit where aerodynamic efficiency is extremely important," Wolff said.
"But assumptions are dangerous – we have seen too many times already this season that the form book can be rewritten from one weekend to the next.
"From what we have seen in the first half of the season, the competitive balance will swing one way and another from circuit to circuit. Red Bull will be a threat if they can build on the performance they showed in Hungary.
"So we need to keep our heads down, stay humble regarding our strengths, diligent about our weaknesses and take the season weekend by weekend. The motivation and determination in the factory are greater than ever."