Horner: Ricciardo and Verstappen Red Bull's 'best ever' F1 line-up

Red Bull Formula 1 chief Christian Horner has underlined his intention to keep Max Verstappen and Daniel Ricciardo together as teammates beyond the end of the 2018 season, saying the pair have formed the team's "best ever" line-up.

Red Bull announced over the United States Grand Prix weekend that Verstappen had signed a new contract tying him to the team until 2020, creating doubt over Ricciardo's long-term future beyond the end of his existing deal that expires in 12 months' time.

Red Bull said it would look to build the team around Verstappen moving forward, but Horner stressed this was not supposed to be a slight against Ricciardo before proclaiming the current line-up to be the four-time champion squad's best-ever.

"What actually I'm referring to is within his engineering group with the people he’s working with, in the same way that Daniel Ricciardo has that confidence in the people around him in his garage and to make his feedback very clear in terms of what he wants from the car," Horner told Motor Sport Magazine while clarifying his comments.

"Fortunately, the way the two drivers drive the car is very similar, their set-ups are very similar. It's not like as a team we have a left or right to choose. What works for one 99 per cent of the time works for the other in how we progress the car.

"I feel that Max and Daniel represent our best ever pairing in Formula 1 and are currently, probably the best driver pairing on the grid. So it’s my priority to make sure we retain that, at least until 2020."

Red Bull's previous line-ups include Ricciardo racing alongside four-time world champion Sebastian Vettel, who in turn was teammates with Mark Webber from 2009.

Webber spent two seasons alongside David Coulthard, who had been with Red Bull since its takeover of Jaguar for 2005, partnering Christian Klien, Vitantonio Liuzzi and Robert Doornbos.