Red Bull team principal Christian Horner believes Daniel Ricciardo chose to leave the Formula 1 team because he was concerned he would end up playing a “support role” to team mate Max Verstappen.

Ricciardo stunned F1 last week by choosing to end his five-year stint at Red Bull and move to Renault for the 2019 F1 season.

“I guess in his mind he’s felt that after five years he feels he needs a new challenge, a new prospectus,” Horner told the F1 website . “I think that obviously he’s chosen to join the Renault team, that he feels they’re in the ascendancy. He knows the Renault product very well from all the time that he’s spent with us.

“And I can’t help but feel that he wants to be [in] a leading role perhaps in a smaller environment. The competition between he and Max is very intense. Max is growing stronger and stronger. And I think Daniel’s just decided that the timing is right for him to check out and try something else.”

Horner said Ricciardo and Verstappen have always had “equal status” at the team but he believes Verstappen’s improving form prompted Ricciardo’s decision.

“He sees Max growing and growing in terms of speed and strength and he doesn’t want to play a support role, I guess, for want of better words,” said Horner. “Not that they’re in any way treated in any way different.”

“I can’t but feel that was perhaps a large part of Daniel’s decision-making,” Horner added. “I could understand if it was to Ferrari or Mercedes. But it’s an enormous risk at his stage in his career.”

Advert | Become a RaceFans supporter and go ad-free

Red Bull was prepared to meet all of Ricciardo’s contract demands, said Horner. “It’s been a bit like trying to convince a girl to go out with you, that’s being pretty reticent.”

“Daniel’s had conversations with Dietrich [Mateschitz, Red Bull owner], with Helmut [Marko, motorsport director], with myself. And we’ve bent over backwards to make it happen.

“But if someone’s heart’s not really in it. And it just felt like that. In the end of the day we gave Daniel everything that he wanted and asked for and it still wasn’t enough I think in his mind to say ‘I want to keep going at Red Bull’. It wasn’t about money, it wasn’t about status, it wasn’t about position or commitment or duration. I think he felt that ‘I need to take something else on at this stage in my career now’. It might be an inspired choice, it might be one that he regrets.”

Horner doubts Ricciardo’s decision was motivated by concerns about Honda, whose engines the teams will use next year.

“He knows the comparative performance of the two engines and reliability. We were even prepared to do a one-year agreement so he was available to Ferrari and Mercedes should they come knocking in 12 months’ time, because obviously they haven’t taken him up.”

Ricciardo made his decision during a flight to the USA and informed Horner in a telephone call last Thursday.

“I thought he was winding me up when he range me yesterday afternoon to say he’s going to Renault,” Horner admitted. “But it then became very clear that was his choice. You have to respect that. Renault are a growing team, they’re committing resource there. Maybe it’s an inspired choice.”

Advert | Become a RaceFans supporter and go ad-free

2018 F1 season