Free practice 1: Ralf heads timesheets

The five-time world champion's best time was a full 1.723s slower than his brother's pace-setting lap of 1m17.015s. Schumacher's Ferrari team-mate Rubens Barrichello also struggled in the new car, which is making its race debut this weekend, and only set the tenth fastest time.

Schumacher Jr has actually set the quickest testing time at the Spanish track prior to this weekend as Williams hopes that aerodynamic development on its FW25 chassis has closed the gap to the leading teams evident when the car was launched.

After topping the earlier free testing session, Jarno Trulli's Renault was second quickest, marginally faster than Spanish team mate Fernando Alonso.

Pat Symonds, Renault's executive director of engineering, said: "Our Friday testing policy proved to be very useful as both Jarno and Fernando had to use the T-car in the earlier session, due to steering problems and an engine failure respectively." That obviously gave the team time to react to problems that would otherwise have hampered them in the official session.

David Coulthard was fourth quickest with the first McLaren-Mercedes, ahead of Olivier Panis's Toyota and Juan Montoya in the second Williams.

Mark Webber, impressive in the early season races for Jaguar but still without any points on the board, started his Spanish weekend with seventh fastest time in the first of the Jaguar R4s, ahead of Jenson Button's BAR-Honda, which was the fastest Bridgestone-shod car, and Cristiano da Matta's Toyota.

Rubens Barrichello was immediately fast with the new Ferrari 2003-GA but with the team concentrating on heavier race fuel loads, ended up just tenth quickest with a lap in 1m18.303s. World Champion Michael Schumacher meanwhile, was five slots further back, although a more accurate picture of the new car will be gained when the field runs fuel-light for the only time during the weekend in Friday's qualifying hour.

Antonio Pizzonia lapped in 1m18.350s, ahead of Ralph Firman, Heinz-Harald Frentzen, Jacques Villeneuve, Giancarlo Fisichella, Nick Heidfeld, Kimi Raikkonen, Justin Wilson and Jos Verstappen.