Speculation about Max Verstappen's future will calm down once Red Bull gives him a winning car, according to team boss Christian Horner.

Verstappen, who is under contract until the end of 2019, is the subject of constant rumours connecting him with Ferrari, but Horner said that it is pointless to consider the future beyond then.

"A contract must reflect mutual interest," he told Formule 1.

"It does not make sense to talk about the longer term because we must first offer him a car that he can win with. I am convinced that once we succeed there will be no team for which he would rather drive."

However, although Red Bull have improved recently, Verstappen has had a particularly bad first half of 2017, marked by reliability problems and now a clash with teammate Daniel Ricciardo.

Asked how Verstappen is coping, Horner said: "Very maturely, especially when you consider how young he is. In England, Max can't even rent a car!

"It's impressive how he deals with the pressure, expectations and interest, especially from the Netherlands. As a driver he is becoming stronger but also as a human."

Asked where Verstappen can still get better, Horner answered: "No-one is perfect, so it's always about improving in small ways.

"That's also exactly the way we work as a team. While already at a high level, Max has the same desire to get more and more out of himself."

Red Bull are third in the 2017 constructors' championship, but 134 points behind second-placed Ferrari.