Horner says Valencia to favour Brawn

Although Brawn has struggled to fight near the top in recent races, Horner believes the Mercedes-powered cars could return to form in Spain, especially after Rubens Barrichello topped first practice yesterday.

However, the Red Bull boss is adamant that if his team can beat Brawn this weekend, it will be a good omen for the remaining part of the year.

"Theoretically this should be their kind of track," Horner told the BBC. "There are no high-speed corners here, it's very hot, it's stop/start.

"This should play to their car's strengths. So we think if we can hang on to them and potentially beat them here, then we are looking in really strong shape.

"But you can't discount the KERS cars as well. I'm sure Kimi and the McLarens are going to be up there. And Fernando looked outstanding yesterday so it's going to be interesting."

He added: "It (on Friday) was difficult to gauge where our competitiveness was yesterday because different people were on different fuel loads. We just focussed on our own programme.

"We had a few little parts that we were testing and trying and getting a few results on. Evaluating those overnight, the boys finished about three o'clock this morning, then back here at seven. They have had a busy time."

Horner admitted his team is still facing a difficult challenge to manage its drivers, with Mark Webber and Sebastian Vettel just 4.5 apart in the championship.

He made it clear, however, that there are no plans for team orders yet.

"It's difficult because nobody has a crystal ball and I think it would be wrong to favour one over the other at the moment," he said.

"Both guys are in the championship hunt and we'll continue to support both of them equally until such time that it becomes either mathematically or impractically possible for one of them to really compete for the championship.

"It will be very interesting to see what Ross is going to do with the same dilemma, because it looked like Rubens was a little bit quicker than Jenson yesterday. Will he let Rubens Barrichello win the race? Maybe they have got the same headache there as well.

"For us it is a great situation to be in and it's great for the constructors. And the drivers, we are letting them race against each other sensibly and it's down to what they do on the track."