Mercedes non-executive chairman Niki Lauda believes that Ferrari still has the upper hand against Mercedes despite Valtteri Bottas' win in Sochi last Sunday.
The German squad dominated Formula 1 in the past three season but this year a Ferrari resurgence has instilled doubt in the Mercedes camp.
"Ferrari is clearly ahead," Lauda told the Austrian newspaper Krone.
"We need to analyse what exactly is not working and take the right steps for Barcelona.
"Because all the teams will bring updates, Ferrari will make a step forward, we have to make two and Red Bull needs to make three," he added.
Mercedes has identified a chronic weakness in the way its W08 deals with tyre degradation, but Lauda insists that's not the only problem facing.
It is said that Mercedes' biggest problem is inconsistency with the tyres, but Lauda says that's not the only issue affecting the Silver arrows' performance.
"We have too much weight in the car, we need to improve the aerodynamics, and above all we need to understand why the new Pirelli tyres do not work as they do on the Ferrari," he said.
Finally, Lauda appeared to agree with reports that suggest Valtteri Bottas is on course for a new contract for 2018, after winning in Russia.
"It was a perfect performance that I never expected," he said.
"It was the right decision by Toto Wolff and myself to get Bottas on board. Bottas is our man."
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