Recently, the 19-year-old Dutchman and his surly father Jos have not categorically rejected rumours Verstappen is linked with a future switch to Ferrari.
At the same time, even though an often clearly frustrated Verstappen is locked in a Red Bull contract until 2019, his car this year has been regularly breaking down.
So when asked if he was relieved when Verstappen finally finished a race recently at Silverstone, Red Bull team boss Horner admitted: “You could say that.”
When asked about Verstappen’s recent outbursts, he told Algemeen Dagblad newspaper: “Of course he has shown some emotion, especially when you stick a microphone under his chin after a bad race, but he has also always been under control.
“This phase in his career is still character building for him, because F1 is not a sport that relies simply on a racquet, bat or ball. So he will only get stronger and more complete,” Horner explained.
He said Red Bull is at least making serious progress with pace and performance, after a less than impressive start to 2017.
“Since Barcelona, there has been real progress in every race with the possible exception of Silverstone, but we’re clearly on the right track,” said Horner.
He said there is no doubt Verstappen will still be a Red Bull driver next year, but admitted that the energy drink-owned team needs to make a step for 2018.
“It’s up to us to give Max a car with which he can win before we talk about the future,” said Horner.
“If we do that, I’m sure there’s no team Max wants to race for other than ours.”
Daniel Ricciardo fastest in Hungary GP both Friday practice
Ricciardo prompts F1’s title competitors that a revived Red Bull can be a force to reckon with, after lapping fastest in practice at the Hungarian Grand Prix.
“We obviously brought some updates here and they seem to be working,” said Ricciardo, who won the Hungarian Grand Prix in 2014.
“I definitely feel like we have found some grip in various areas and taken a step in the right direction.
“Ferrari seemed to find a bit more pace in the afternoon but I still managed to stay ahead so all signs are good.
“I’m sure the other teams will bring a bit more tomorrow, but I also think we have a bit more to find.”
Verstappen was fourth and sixth respectively in the Friday practice.