Although the Russian had a difficult start to the campaign, which was hindered by a lack of mileage in testing and the early races, he has recovered strongly since then.

At the Hungarian Grand Prix he delivered the best result of his career with a strong second place, and in Belgium last weekend he finished fourth.

The improvement in his form has left team boss Christian Horner relaxed about his driver situation, with Daniel Ricciardo already locked in to a long-term deal.

"I don't see any reason to change it [the driver line-up for 2016]: but we don't have to be in any rush to make a decision," said Horner, referring to the fact that the contracts with Red Bull drivers mean they can be placed at either of its F1 teams.

"Both drivers are under long-term contracts so it is a successful partnership and it is working well."

Verstappen future

In the longer term, it is obvious that Max Verstappen has shown himself a potential future F1 winner with his ongoing strong performances this year.

However, Red Bull may feel that he needs another season at Toro Rosso before he is ready to jump up to the main team, which could also come at a time of it changing its engine plans.

It may also find it needs to graduate him, with rivals potentially trying to lure him away with the offer of race-winning machinery.

Red Bull is pushing for a switch to Mercedes for as early as 2016, but much will depend on if it can escape the final year of its contract with Renault.

Horner admitted that his outfit was undergoing a period of change, with tech chief Adrian Newey having stepped back a bit early this year.

"It is evolution," he said. "In any team or business, it has to keep evolving. Nothing stays static forever. The drivers we have got are a very strong pairing.

"I am very happy with the driver pairing we have got. Adrian is still very much involved but just in a slightly different manner.

"We have talent that is emerging and like in any business it has to continue to evolve, and we are going through that process of evolution."