Sebastian Vettel's decision to leave Red Bull for Ferrari in 2015 was "sad but understandable", Christian Horner admits

The German won four consecutive world championships with the Milton Keynes-based outfit between 2010 and 2013, but their period of dominance was ended by the introduction of turbo hybrid engines in 2014.

In that final year, Vettel failed to win a race and was largely out-classed by new teammate Daniel Ricciardo, who claimed three wins and finished third in the Drivers' Championship.

And reflecting on that period, Horner perhaps surprisingly didn't see Seb's move to the Scuderia as a "mistake".

“Do you know what? At that time I don’t think it was,” the Red Bull boss said via Sky Sports.

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“We weren’t in a competitive position at that time. Mercedes had a massive advantage, Ferrari looked like they were on the ascendancy. Renault didn’t look like they were gonna get themselves sorted out anytime soon.

“So no, we couldn’t compete with it. It was the right thing at that point in time for him.

"He had a desire to follow in the footsteps of Michael Schumacher. And you know, the lure of Ferrari for him at that time when we couldn’t offer a competitive car, it was understandable. It was sad but fully understandable.”

Of course, Vettel's time in red would ultimately end in disappointment as they failed to win any championships despite positive starts in 2017 and 2018 before parting at the end of 2020.

The 53-time Grand Prix winner then joined Aston Martin before announcing his retirement from F1 at the end of 2022 back in Hungary.

“On the one hand, it was sad to see that announcement, but on the other, I think the timing’s right for him,” Horner commented.

“He was a massive part of our team. He was a pleasure to work with. He was committed, he was unrelenting in his pursuit of performance, [he was] probably the hardest working driver I’ve ever come across and beyond that, just a really nice guy.

“We had so many special moments those four World Championships. There were days that he was just in a league of his own. What he’s achieved is quite outstanding and [I] just wish him all the best for the future.”