Red Bull boss Christian Horner has warned his rivals that the best is yet to come from the cars that enabled Sebastian Vettel and Mark Webber to dominate the Chinese Grand Prix.

Horner insisted “the sky's the limit” after watching Vettel cope brilliantly with appalling conditions at the Shanghai International Circuit to give the Milton Keynes-based outfit their maiden Formula One victory.

It was the 21-year-old German's second win — his first was also in the wet, for Red Bull's junior team Toro Rosso, in Italy last year — while Webber achieved a career-best second place less than five months after the Australian broke a leg in a cycling accident.

Britain's Jenson Button consolidated his championship lead by coming home third but he is concerned by the speed of the Red Bulls, which have yet to be fitted with the controversial diffuser that made his own Brawn GP car unbeatable in Australia and Malaysia.

He admitted: “We couldn't challenge Sebastian and Mark. They were immensely quick.”

And they could be quicker still when the Sakhir circuit in Bahrain hosts the fourth round of the title chase next Sunday. Team principal Horner said: “China was the breakthrough result for us.

We can see that we're competitive with both drivers, so I think the sky's the limit. The car's got a great aerodynamic package. Imagine when we get our double diffuser.”

That won't happen in Bahrain, even though chief designer Adrian Newey remained in Milton Keynes at the weekend to work on a copy of the diffuser exploited so effectively by Brawn GP.

But there will be other new parts appearing at the weekend which will be aimed at making the Red Bulls as competitive in what is bound to be a dry race as they were on the rain-soaked track in Shanghai.

Vettel, who started from pole position yesterday, said: “An update can make a huge difference. We are pushing extremely hard to make the car faster but I'm very happy that the car is fast already and able to compete with the best teams.

Basically, we will try to stay on top and be the best team.”

That has thrown down the gauntlet to Brawn GP.

Having committed most of last year to developing a car for this season's new-look Formula One, they were able to set the pace in the opening two races. But Button did warn that other teams would not take long to catch up and he has been proved right.

Horner is proving a canny strategist and the new partnership of Vettel and Webber is looking ominously strong.

Horner said: “Sebastian has been a member of the Red Bull family for some time, so he has been well known to the team. His enthusiasm and commitment has really lifted the team and he is bringing the best out of Mark as well.

“They are pushing each other hard. They are driving the wheels off what is a very good car and it is really a very positive atmosphere inside the team.”

Despite the distractions of the Liargate' scandal and team chief Ron Dennis's decision to sever all connections with F1, McLaren are another team who have made technical progress as evidenced by Heikki Kovalainen and Lewis Hamilton finishing fifth and sixth in China.

Hamilton might have challenged Button's team-mate Rubens Barrichello for fourth place had he not spun twice. Maybe off-track pressures are getting to the world champion, who admitted: “I love racing in the wet and that was one of my worst performances.”

Ferrari's Felipe Massa and Kimi Raikkonen came away without a point for a third successive grand prix, giving the Italian outfit their poorest start to a championship since 1981.

Michael Schumacher, who won five of his record seven world titles with Ferrari and is retained as an advisor to the team, believes the crisis is so bad that they may have to write off this season and concentrate on next year.

Team boss Stefano Domenicali admitted such a drastic course of action might be considered after the first race in Europe next month. “We will see where we are after Spain,” he said.