Highlights - Barrichello wins in Valencia
By Andrew Benson
BBC Sport in Valencia
Championship leader Jenson Button has admitted he needs to find his form if he is to keep his title bid on track.
The Brawn driver finished only seventh in Sunday's European Grand Prix as team-mate Rubens Barrichello won the race to close to within 18 points.
"It's still a big gap so it's not too bad," he said. "But it seems the people behind me are jockeying for position.
"Sooner or later they will start closing the gap unless I do something about it."
Veteran Brazilian Barrichello believes he can still close the gap to Button in the remaining six races.
"Of course it puts me in a better situation in the championship," the Brazilian said. "I just have to keep working and I think it's very possible.
"We will fight very hard but in a fair way."
We're in a position now where both drivers have proven they can win [the championship]
Brawn chief executive Nick Fry
Button has not finished on the podium since winning the Turkish GP on 7 June, and even though Brawn returned to competitiveness in Valencia he was not able to join Barrichello at the front.
The Englishman took solace in the fact that despite his poor result he still extended his lead over the Red Bull drivers Mark Webber and Sebastian Vettel, who had an even worse weekend.
Webber, who battled with Button for more than half the race in Valencia, could finish only ninth as the Red Bulls struggled to find any pace on the stop-start street circuit and is now 20.5 points behind Button.
Vettel, who retired with an engine failure, has slipped to fourth place 25 points adrift of Button with a maximum of 60 points available from the remaining six races.
But Button - and the rest of F1 - expects Red Bull to set the pace at the Belgian Grand Prix next weekend.
The high-speed track suits the Red Bull car and there remain questions about the Brawn car's ability to be competitive in the lower ambient temperatures that are usual at Spa-Francorchamps.
Brawn are hopeful they have found a solution to that problem, but will not know until they run their car in practice on Friday.
"It's been a tough weekend for them (Red Bull) but also we are going to a circuit where they will be very quick," Button said.
"I have gained a couple of points on Mark which is good but I have lost a lot of points to my team-mate Rubens.
Button 'happy' for Barrichello
"I didn't expect my team-mate to finish so far ahead of me. I need to solve that for the next race.
"We have got to go to Spa positive and ready to have a good weekend. We have got to do a lot of work on Friday to make sure our car is good in the cold conditions but I think we know what we are doing.
"We need to qualify well and if we do that we can have a good race. The problem is when you get stuck in the pack things happen and you can't do anything about it because you just don't have the speed.
"Rubens did a great job this weekend and he deserves the victory for sure.
"It's been a long time for him, five years, and I am happy for him. For sure I would rather be on top of the podium but I am not. He did the better job this weekend and he didn't make a mistake so he won.
"But we did what we came to do in a way we came to beat the Red Bulls and claw back a couple of points on a circuit that our car suits."
Button qualified only fifth in Spain, and a poor first lap put him down to ninth, from where he was not able to use the full performance of the car.
He set fastest laps once he was clear of traffic in the last stint of the race but by then he had lost too much ground.
Team boss Ross Brawn said he regretted not putting Button on a different strategy that might have enabled him to get further up the field early in the race.
"There was not much we could have done today," Brawn said. "It was frustrating with Jenson. I think when we look back maybe we should have been more aggressive with strategy to put our guys at the front because he got bogged down with a lot of traffic and he had a quick car he couldn't do anything with.
"It worked for Rubens but it didn't work for Jenson."
Meanwhile, Brawn chief executive Nick Fry thinks both drivers are capable of winning the 2009 drivers' championship following their results in Valencia.
"We're in a position now where both drivers have proven they can win," he said.
"Rubens has shown what he can do and Jenson's won six, so I wouldn't bet against either of them."