Pedro de la Rosa gave his McLaren team a boost ahead of Sunday's San Marino Grand Prix when he finished comfortably ahead of his rivals in practice here Friday.
De la Rosa, who raced for the team in Bahrain but returned to his usual third driver role this weekend, beat his session-leading lap in the first session with a time of 1:20.484 in the second to end the day on top of the pile.
"So far it has worked quite well," said de la Rosa. "I think there are still a few tenths in the car, we have to work a little bit on the suspension especially over the kerbs but so far it is quite good.
"We are looking for a podium finish here, I am not sure about winning. I think qualifying will be 70 percent of the outcome of the race because it is difficult to overtake here and we have to work on improving our qualifying performance."
But Jenson Button signalled his and BAR-Honda's intent to return to the sharp end of Formula One this weekend when he finished second fastest, albeit 0.568 seconds behind the lead McLaren.
Button, whose team have failed to finish a race so far this season, was confident of improved pace heading into this weekend's event after a strong performance in testing in the last two weeks.
He said: "We have made a good step forward in reliability and aerodynamics and it is looking very positive. It's only Friday and you cant say too much but everything went very smoothly for us.
{{/usCountry}}He said: "We have made a good step forward in reliability and aerodynamics and it is looking very positive. It's only Friday and you cant say too much but everything went very smoothly for us.
{{/usCountry}}"The car is much better to drive and it is more predictable, which is a big thing in Formula One, consistency."
The British driver, whose car has an improved engine and aerodynamics, finished with a time of 1:21.052, set early in the session, to split the McLaren drivers and leave Kimi Raikkonen, of Finland, third.
Toyota test driver Ricardo Zonta finished fourth fastest with Spaniard Fernando Alonso, the world championship leader, fifth fastest for Renault despite completing just 10 laps.
World champion Michael Schumacher finished right behind in sixth place with his Ferrari team-mate Rubens Barrichello seventh as the Italian team continued their fightback from a disappointing start to the year.
Alex Wurz, who is substituting for the injured Juan Pablo Montoya this weekend, put his McLaren in eighth place and Giancarlo Fisichella and Takuma Sato completed the top ten for Renault and BAR respectively.
With 30 minutes gone Button was on top of the timesheets, almost a second faster than closest rival Barrichello and almost 1.2 seconds faster than third-placed Fisichella.
Dutch driver Robert Doornbos suffered the first major incident of the session when he spun his Jordan at Aqua Minerale and hit the barriers after crossing the sand trap but he recovered to return to the pits with only a damaged nosecone.
Raikkonen bumped Barrichello down to third with 15 minute to go and Alonso, who like Fisichella sat out the morning session, finally exited the pits and immediately set a top-ten time.
De la Rosa, who had finished fastest in the morning practice session with a time of 1:21.060, then moved ahead of Button by more than half a second with five minutes to go.
Christijan Albers, in the new Minardi PS05, was the only driver not to complete a lap and most of the race drivers limited their running but Ferrari completed a more than 40 laps between their two drivers.