DEFENDING world champion Kimi Raikkonen topped the time sheets as Ferrari dominated the opening day's practice ahead of Monday's (EST) Spanish Grand Prix.
The 28-year-old Finn, who is this year's early season leader, clocked a best time of one minute, 21.935sec in the second session having been fastest in the morning with 1:20.649.
His Ferrari teammate Felipe Massa of Brazil was second fastest in the morning and fifth in the afternoon when his compatriot Nelson Piquet clocked the second best time for Renault.
"That was good and I am very pleased with this first day of practice,'' Raikkonen said.
"We did the work we needed to do and I had no problems. That is the most positive thing - and the balance of the car is good.
"There is always room to improve, but the handling of the car is good and it was good on both sets of tyres we used. I am happy, but of course we don't know what the other teams are doing. I guess it will be a close fight. It usually is.''
Local hero and twice former champion Fernando Alonso in the second Renault was third fastest as the French team played to the crowd on the opening day of the meeting.
Alonso said in advance of the Grand Prix that he did not expect his team to be in the scrap for a podium finish and his team's effort on Friday suggested they were running with light fuel loads.
Australian Mark Webber was sixth in the afternoon at 1:22.238, two places better than Red Bull teammate David Coulthard (1:22.289).
Briton Lewis Hamilton, 23, who won the season-opening Australian Grand Prix for McLaren but then suffered two increasingly disappointing outings, wound up 11th for the Mercedes-Benz powered team.
That put him one place ahead of Pole Robert Kubica of BMW Sauber and two in front of Germany's Nick Heidfeld in the second BMW, the team that currently leads the constructors championship.
Hamilton's McLaren teammate Heikko Kovalainen of Finland was down in 16th place, a result that appeared to suggest that the Anglo-German team were experimenting with their settings and fuel loads rather than seeking out and out speed.
The session was run in dry, warm and sunny conditions with an air temperature of 24 degrees, rising to 25 as the Spanish spring arrived, and a track temperature of 37 degrees.