Christian Horner has come under heavy fire from F1 driver turned pundit Ralf Schumacher for controversial claims in his new book.

The former Red Bull team principal, who was sacked from his role in July 2025, released his new memoir 'Drive' last week and it came complete with a number of stunning revelations.

One of those bombshells was Horner claiming that former Red Bull colleague and adviser Helmut Marko did not want the team to sign the now four-time world champion Max Verstappen.

According to Horner, Marko had said: “The father's [former F1 star Jos Verstappen] a nightmare… We don't need this one".

Marko himself has already poured scorn on Horner's book - describing it as "a collection of untruths of such a low calibre that I won't address them".

Schumacher accuses Horner of 'complete lie'

And now Schumacher - a leading analyst for F1 broadcaster Sky Sports in Germany - has waded in to criticise Horner and defend Marko.

Schumacher - speaking on the Backstage Boxengasse podcast (per BILD) - said: "That's an absolute no-go, the story is a complete lie. Allegedly, Marko said that Max's father, Jos, was a nightmare.

"But the story as I know it goes like this: Helmut Marko approached Max when he was just 11 years old. Jos actually said that it was too early for him. And then the doctor got a little miffed and said, 'If he doesn't want me, then so be it.'

"Years later, they met again in Formula 3, and that's how this partnership developed. That had little to do with Christian Horner. I don't know what's going on in Horner's head."

Schumacher says Horner is ruining his legacy

Schumacher also spoke about the Horner/Marko fallout during Sky's coverage of the weekend's US Grand Prix action in Austin, admitting he has been disappointed by the 52-year-old Englishman.

"Unfortunately, it's nothing new with Christian Horner that he's occasionally been in poor taste," he began.

"I think that's a shame. He's ruining all his own hard work, because he and the team have been very successful.

“He significantly influenced the engine with which Red Bull won races here. He brought in these people and then does something like this. It's just a shame and sad.”