Christian Horner does not fear Max Verstappen will leave Red Bull to go up against Lewis Hamilton at Mercedes next season.

Verstappen enhanced his glowing reputation with a remarkable drive to victory in Austria on Sunday.

The 21-year-old Dutch star is signed up until the end of 2020, but he has a release clause in his contract which could leave Red Bull vulnerable to an approach from Mercedes.

Hamilton's team-mate Valtteri Bottas is on a one-year rolling deal, with the Finnish driver's future beyond this season uncertain.

"There has been speculation about Max's contract, but it is purely speculation," said Red Bull team principal Horner.

"Max is very happy within the team and he believes in this project. Days like today only endorse that, so I have no doubts about Max.

"He has driven phenomenally well at every single grand prix to date this year. He is using the experience he has gained in his career, and his pace is beyond doubt. He has very much become the complete package.

"We want to make sure we can provide him with the tools to challenge for the championship, so that is our target over the next 12 months."

After a poor start to Sunday's race, Verstappen delivered a thrilling performance to snatch victory from Ferrari's Charles Leclerc with just two laps remaining.

Asked if Verstappen's display led Horner to think he has the best driver in F1, he replied: "I have thought that for a little while."

Verstappen survived a post-race investigation into his winning move on Leclerc at Turn 3.

Leclerc fell off the track as the two young stars battled for victory, but former world champion Nico Rosberg felt the stewards should have punished Verstappen.

Rosberg was hit with a 10-second penalty when he collided with Hamilton at the same corner in 2016.

"The question is whether Max, on purpose, ran wide and turned in late because he knew from the lap before that that was the only way to win the race – to run Leclerc out," said Rosberg.

"I think he turned in late. He was well off his usual line. He usually hit the apex there, one of his strongest corners. He turned in late and unfortunately he needed to get the penalty."

Hamilton, meanwhile, took the chequered flag in fifth, his worst finish in more than a year.

The British driver, however, will head to Silverstone for his home race a week on Sunday with a 31-point championship lead.

"This wasn't the best weekend for me, but over the years I've learnt to notice the lessons that come from difficult days," said Hamilton in a post to Instagram.

"I made two mistakes this weekend which for me is rare but were costly. Tomorrow's a new day. Back to training and getting myself right for the British Grand Prix."