Daniel Ricciardo is enjoying success despite engine power issues. Credit:Getty Images Horner has direct experience of trying to keep the peace between warring teammates, refereeing the bitter clash between Mark Webber and Sebastian Vettel at RBR from 2009-2013. Ricciardo and Verstappen have a harmonious relationship out of the cockpit and while intensely competitive on the track, there is no rancour in their racing. "You can see that they actually quite like each other out of the car, but there's a fierce rivalry, certainly, on the circuit," Horner told Fairfax Media ahead of the British Grand Prix at Silverstone on Sunday night (AEDT). "They're pretty straightforward individuals. "So unlike some of the previous drivers we've had, they're pretty easy to deal with, I'd say."

Horner says Ricciardo and Verstappen get along. Credit:Getty Images According to Horner, managing the on-track rivalry between Ricciardo and Verstappen is easier because they're much closer in age and experience than were Webber and Vettel, who won four consecutive F1 world titles with RBR before joining Ferrari in 2015. "There's not the tension that there was, certainly, in Seb's and Mark's time, but they (Ricciardo and Verstappen) have their moments," he said. "Generally, though, they've been very, very good to deal with. "I mean, between Seb and Mark, there wasn't the respect that there is between Dan and Max. So it was a very different relationship. Sebastian was at the top of his game, Mark was in the later years of his career, and, of course, there were tensions that sometimes boiled over." Horner, who is married to former Spice Girl Geri Halliwell, credits Ricciardo's sunny disposition – highlighted by his ever-present grin – for diffusing Verstappen's more volatile nature.

"Absolutely," he said. "Beneath that big smile is a very competitive, hungry young man. They all have their moments, but generally, we're lucky in the fact that the two guys get on pretty well, anyway. "There's a respect between the two of them. Of course, they're fierce competitors, but that only helps." Perth's Ricciardo, 27, is unusual, if not unique, among elite athletes for being personable rather than aloof and yet absolutely merciless – but scrupulously fair – in wheel-to-wheel combat. "Usually, guys that are at the top of their game have that ruthless streak of self-arrogance and, usually, are not particularly nice individuals, whereas Daniel totally breaks that mould," Horner said. "He's a very personable guy – what you see is what you get. He always has a big smile. Everyone in the team loves him, he's hugely popular with the fans and, yeah, he's a pleasure to work with." Ricciardo is a warrior racer and an opportunist, as evidenced by his come-from-behind victory in last month's chaotic Azerbaijan GP.

He followed that with a fighting third place in last Sunday's Austrian GP, his fifth podium placing in a row despite his Red Bull being no match for the pacesetting Ferrari and Mercedes in outright speed. "His restarts in Baku and some of the passing moves he made were absolutely first-rate," Horner said. "He's like a dog with a bone when he sees an opportunity. He just won't let go and he just never gives up. "He'll go for those opportunities and he's been tremendously successful at taking them." Horner also maintained that their competitive spirit is driving the team forward, often overcoming the Renault-powered Red Bull RB13's horsepower shortfall. "From a team point of view, it's great," he said. "To be on top of one or the other, they have to be right at the top of their game."

Horner is convinced that Ricciardo – who has won five F1 races in uncompetitive cars – and 19-year-old phenomenon Verstappen – who won on debut with RBR last year, but has suffered failures in five out of the last seven races this year – will be future world title contenders. "Daniel has all the potential to achieve that," he declared. "I think both the drivers we have are both potential future world champions and that's a very fortunate position as a team to be in." Amid speculation that Ferrari had made overtures to sign Ricciardo or Verstappen to replace Kimi Raikkonen next year, Horner confirmed that both were tied to RBR in 2018. "Their contract durations are slightly different, but both of them are under contract for next year," he said. He revealed that Ricciardo's existing deal with RBR runs until the end of next season.

"He's on a five-year contract and next year's the fifth year," he said. Following Ricciardo's third place last Sunday at the Red Bull Ring, which is a power-dependent track, Horner expected him to be more competitive at the fast-but-flowing Silverstone track this weekend. He thought Ricciardo and Verstappen would be genuine contenders in the Hungarian GP at the end of the month on the slower, tighter Hungaroring. "Hopefully, Silverstone will be better for us and, certainly, at Budapest we should be in better shape." Longer term, Red Bull Racing is waiting for power unit supplier Renault to finally catch Mercedes and Ferrari in the power race for Ricciardo and Verstappen to be able to challenge for the world title.

"Horsepower is the predominant area (of weakness)," Horner said. "It's getting better, but we still have a little bit of ground to make up there. I think this year with the chassis, we started out on the back foot, but we've developed the car well and we're getting onto the front foot now. "But our biggest single area of deficiency is just outright horsepower, which the guys with the engine are working very hard to improve it. The chassis is pretty much on a par with the Ferrari and the Mercedes now." Horner pointedly doesn't refer to Renault by name following a reluctant renewal with the French car-maker after a winless 2015 season, with the petrol-electric hybrid power unit rebadged TAG-Heuer to fund the continued alliance. He is cautious about the likelihood that the engine-maker-that-shall-not-be-named will bridge the performance gap by next year – although, in any event, RBR is contractually committed until the end of the current engine rules. "I hate to put time scales on these things because they're very difficult to predict," he hedged. "But, yes, I think they're making good progress.

"We don't have any option to change. We have a commitment with our current engine supplier until the end of 2020, so we go to church every week praying for a few more horsepower."