Jenson Button continued his strong start to the Formula One season by setting fastest time in one of today's two practice sessions for the Spanish Grand Prix in Barcelona.
The Brawn GP driver, who has won three out of the four races so far this season, posted the quickest lap during the opening practice session, before Williams hotshoe Nico Rosberg went fastest in the second stint.
The Barcelona race is being seen as a crucial round of the championship, because it starts the European leg of the season and many teams have introduced updates to their cars after the opening races. Button had been expected to enjoy a decreased advantage at Barcelona, given that many of the chasing teams are introducing new aerodynamic ideas similar to those utilised on the Brawn.
However, Button put in a late flying lap in this morning's session to go 0.355sec quicker than the second-placed Toyota of Jarno Trulli. BMW showed improved form, with Robert Kubica and Nick Heidfeld in third and fourth.
Rosberg led Williams team-mate Kazuki Nakajma home in the second session, with Renault's Fernando Alonso in third. Button was sixth.
Despite his strong display, Button declared himself concerned with his car's set-up. "Qualifying and the race at the important ones. Today is not important to be quickest," he said. "It's more about getting a good feeling and a good balance.
"I'm not there yet and I'm a bit disappointed with the way the car is at the moment. Hopefully we can improve overnight, I know that we will because we know which direction to go."
Reigning champion Lewis Hamilton, meanwhile, suffered a frustrating start to his Spanish GP weekend. He was 14th and 13th into today's two sessions. "It's worse than I expected," said the McLaren star. "We are pushing but unfortunately we tried some upgrades and they are not working for me. There has been no improvement to the car whatsoever."