Dr Helmut Marko has nominated Sebastian Vettel as the world championship favourite for 2018.
That is despite the fact that Ferrari driver Vettel, once a Red Bull protege of Marko's, lost his title lead two weeks ago at Baku.
Marko told Sport Bild: "He is my world championship favourite.
"Sebastian looks even more mature and balanced than he did last year. But also Ferrari has the better car. Now they have to not make any mistakes."
Marko played down speculation Ferrari has moved ahead of Mercedes due to several controversial technical solutions on its 2018 car.
"The FIA looks very closely, for example with the oil, and they say everything is correct," said the Red Bull official.
"There was speculation about the batteries and this too will be looked at by the FIA, but it didn't come from us.
"For us, the Ferrari is legal, because we trust the FIA."
The championship continues on Sunday with the Spanish Grand Prix.
