Berger, who has long been close to Dietrich Mateschitz and was once part of the management of Toro Rosso, insisted Red Bull needs the best possible line-up to have a shot at defeating Mercedes pairing Lewis Hamilton and Nico Rosberg.

“I think Mercedes have the best two drivers they can have," Berger told Motorsport.com.

"I think the other teams are realising that if you want to beat Mercedes, when they have a big technical advantage, and especially on the engine, even if you put yourself on the same level, you have to beat these two drivers to win the constructors' championship.

"Because these two drivers are each in his way outstanding, and in a combination they are unbeatable.

“That's why Red Bull reacted very strongly with Max Verstappen, they said 'we have Ricciardo, somebody able to compete, but we need another one, because they have Nico and Lewis.'

"They thought: 'If we get Verstappen and Ricciardo we can at least put Ferrari under pressure, and next year we have a chance to compete with Mercedes with two big guys'.”

Red Bull on the up

Berger also reckoned that the RB12 is the best chassis in the current Formula 1 field - and that Red Bull can now see "a light at the end of the tunnel".

“I think at Red Bull you feel a very big dynamic going on,” Berger said. “You know, in F1 you always have these cycles - three years very strong, or four years very strong, and then it's going down.

“It's important not to lose many of your key players at this time. And I think Red Bull managed very well to keep all their group together.

"They know they have always done a fantastic job, they know most of the time they have the best car, and this year they definitely have it.

“They always knew that Renault had to do their homework, and it looks like Renault are doing something, and it looks like the steps are forward.

"Winning in Spain, even if Mercedes stopped, but beating Ferrari, it was already a little bit of a light at the end of the tunnel.”

Future title contender Verstappen

Berger says that Verstappen is a potential future champion: “He's still young, he still has to prove everything, but for me he's a clear championship candidate in the future.

"I watched Max very closely in karting, because my nephew [Lucas Auer] was racing with him. And then I watched him in F3, because I was working with the FIA.

"I remember one day my sister, the mother of my nephew, said, 'Why do you always talk about this Max Verstappen?' I said 'It's very simple, he's outstanding.'

"So the racecraft of Max Verstappen I saw before – I know he's a good candidate for the future.”