Button pleased after 'amazing' win
By Andrew Benson
BBC Sport in Bahrain
Jenson Button expects his Formula 1 rivals to turn up the heat for the rest of the season following his victory in Sunday's Bahrain Grand Prix.
The Brawn driver leads the championship by 12 points but he said there was no guarantee he would keep his advantage at the next race in Spain on 10 May.
"We don't know where everyone's going to be when we get to Europe," he said.
"It's exciting for F1. There's been change already and I think there will be more. It's just what F1 needed."
Button's team boss, Ross Brawn, said the team were planning updates to their car for the Spanish Grand Prix at Barcelona's Circuit de Catalunya.
While other teams have added new parts to their car over the course of the first four races, Brawn's car is in the same spec as it was for the Australian Grand Prix at the start of the season.
Brawn takes satisfaction from 'tough' win
"We were just happy to get to Melbourne, there was nothing left in the cupboard - the car we had in Melbourne is the car we have now," Brawn said, recalling the team's battle to survive in F1 following former owner Honda's decision to quit last December.
"Since we launched the car and we started testing obviously the factory has been working on improvements and we will have the first stage improvements in Barcelona.
"So we are a little bit behind perhaps, but that is just a legacy of what we have had to put together.
"Also I think our approach in practice has been to concentrate on the race set-up and of course, when we had a margin of performance at the beginning, that was fine. Now, we don't have that margin people are getting past us in qualifying.
"We have got a new aerodynamic package at Barcelona, we have got some weight saving - some of the things we had to do on the car to get it to Melbourne are not as nice as we would have liked - and hopefully some improvements with the engine in terms of drivability, so it's in lots of areas.
"I am optimistic of a good step [forward in performance]."
But Button emphasised that other teams also had their own new parts to introduce in Spain - among them Red Bull, Toyota, McLaren, Ferrari and Renault, the teams that filled the remaining points positions in Bahrain.
"We've had four races and we've picked up points while people have had reliability issues at the start of the season," Button said.
"But everyone's got new bits coming. I'd say the McLarens seemed to be a bit more competitive this weekend.
"You can't forget McLaren. We should all have new cars in Europe. It's positive that we've got some points on them already."
The decisive moment in the race came when he was able to pass Lewis Hamilton's McLaren at the start of the second lap, while his main rival for race victory Sebastian Vettel was stuck behind the world champion for the entire first stint.
That ensured Button was able to emerge in the lead after the first pit stop period and thereby extend his advantage sufficiently to win the race.
"I'd say it was my finest first lap of my career, that's for sure," said the 29-year-old, who stopped short of saying that he had produced the best drive of his career.
"I was very happy with the race. I didn't feel I had put a foot wrong. It's nice to be in a car where you can show what you can do.
"This was a tough race for us. This weekend we haven't had the pace we've had the first two races. I don't know where it's gone. I guess these guys have just caught up."