Cape Town - Christian Horner reckons Sergio Marchionne would never have brought Alfa Romeo back into Formula 1 if Ferrari really were considering quitting the sport.
Marchionne, who is in charge of Ferrari and the Fiat Chrysler group, has reiterated his threat to pull Ferrari out of Formula 1 if the new 2021 engine regulations do not suit the Scuderia.
However, Red Bull boss Horner believes that is more bluster than intent.
"They (Alfa) come under the same management as Sergio so I can't believe he'd have brought Alfa Romeo in for Ferrari to be leaving in a couple of years," he told Reuters.
"I think it demonstrates that Formula One is obviously working and creating the recognition, otherwise the group wouldn't have brought the Alfa brand into Formula One."
He added: "Formula One needs Ferrari and Ferrari needs Formula One.
"It's a marriage of convenience in many respects but both entities ultimately need each other. And we certainly want Ferrari in Formula One.
"A Formula One with Ferrari in, it's one of the biggest brands in the world and they are a great team to compete against."