Ferrari's Kimi Raikkonen set the pace in Friday's practice for the European Grand Prix, as drivers got their first racing experience on the new Valencia street circuit.
The Finnish world champion had a best lap of 1 minute, 39.477 seconds on the 5.4-kilometer (3.4-mile) course in the afternoon session to narrowly edge Renault driver Fernando Alonso, who was second in 1:39.497. Honda's Jenson Button was third with 1:39.546, while Ferrari's Felipe Massa and overall leader Lewis Hamilton of McLaren rounded out the top five.
"Today, our weekend got off to a good start, but obviously it is far too early to say where we are compared to the opposition," Raikkonen said. "The setup we have found today is not bad, but there is still plenty of room for improvement."
Sunday's European GP comes after a three-week break following the Hungarian GP. Hamilton leads the standings with 62 points, five ahead of Raikkonen and eight in front of Massa.
Several drivers struggled on the unfamiliar circuit on Friday, with Massa and Nelson Piquet Jr. among those that veered off the track. Nico Rosberg spun around in his Williams when going through a turn, and narrowly avoided crashing into Red Bull's Mark Webber.
Alonso, however, felt comfortable driving on home territory for the second time season.
"The first day was difficult for everybody, especially to get the braking points. It's very hard on breaks," said the Renault driver, who has struggled this season and sits eighth in the standings with just 18 points.
But Alonso, who won two consecutive world championships with Renault, said the team is constantly getting better.
"We started the season not in a perfect way," he said. "We keep improving the car, race after race and we are in a position now to be in the top six in qualifiers and, in the races, to get points."
Hamilton was also optimistic after clocking 1:39.712.
"Considering the dustiness of the track we made a very promising start on the setup this morning," Hamilton said. "We were able to go quicker on each run without changing too much and we took a very good baseline into the afternoon session ... We're in pretty good shape and I'm looking forward to tomorrow."
McLaren teammate Heikki Kovalainen, who secured his first F1 win in Hungary after Massa's car broke down on the final lap, had the sixth best time with 1:39.954.
"The track was very green this morning which meant there was little point in making big changes to the car," Kovalainen said. "In the afternoon we made a number of changes which seemed to pay off for us _ by the end of the session the car was working well and the balance felt really good. Today's progress was very encouraging."
The drivers have a final practice session Saturday before the afternoon qualifier to decide pole position for Sunday's race.