Max Verstappen is clearly "the most important part" of Red Bull Racing.

That is the frank admission of Dr Helmut Marko, who insists that while the energy drink owned team is starting 2023 as the clear favourite, the season will also be "a challenge for us".

"The main part is still to come," he told Kleine Zeitung newspaper. "Because as the season progresses, the competitors will develop and bring multiple updates.

"That's why it's so important that we have a really good start to the season."

Indeed, as world champions, the new sliding development scale means that Red Bull was already allocated the least wind tunnel time for 2023.

And a further 10 percent reduction on top of that was also added by the FIA as part of Red Bull's budget cap overspend penalty.

"We had to make very precise selections in the wind tunnel," said Marko. "We went in with a specific project that had to work on the first try."

The golden goose for Red Bull, however, is the back-to-back world champion Max Verstappen - now already regarded as one of the greatest F1 drivers of all time.

"We all knew he was very fast," Marko told De Telegraaf newspaper. "But when it comes to managing his tyres, he's gotten a lot better.

"Lewis Hamilton may have had an advantage earlier due to his experience, but Max is now at the top in that area as well."

And just by having the Dutchman in the car, Marko said, is "the biggest motivational factor" for the entire team.

"It makes it so much easier to attract brands and sponsors, because everyone wants to work with him," he said.

And so Red Bull is focused on keeping the 25-year-old happy.

"I was a little concerned once when we were in the engine situation with Renault," Marko admitted.

"We were always open with Max. We told him about the situation, about the problems and about the possibilities. When we wanted to do business with Honda, we first talked to him and explained how we envisioned it."

Verstappen was also involved in the Porsche and Ford talks, Marko added.

"Precisely because he is the most important part of our team," said the 79-year-old Austrian, who then referred to the duration of Verstappen's long contract.

"If Max has had enough after 2028, he will stop," Marko said.

"He is just the type who can make such a decision. And I won't then see him walking around in the paddock as a television analyst or anything like that."