**Fernando Alonso got his Ferrari career off to a flying start by setting the fastest time of the major Formula 1 test at Valencia on Wednesday.**The double world champion took over from Felipe Massa and set a best time of one minute 11.470 seconds - more than half a second clear of the field.
Pedro de la Rosa’s Sauber was second, ahead of Michael Schumacher’s Mercedes, which was 0.968secs off the pace.
McLaren’s Jenson Button ended the day 1.481secs slower than Alonso.
Winter testing times are notoriously unreliable indicators of form because fuel loads, tyres and track conditions can make a significant difference to performance.
But Mercedes boss Ross Brawn admitted that his team were struggling a little and that Ferrari appeared to have the quickest car in Valencia.
Brawn said: "On full tanks yesterday (on Tuesday) we didn’t look too bad but we’re a little bit off on pace and (there are problems with) the handling and balance of the car which we can fix for Jerez (testing next week). We know what the problem is.
"Of course the other teams will be progressing as well. We are not as quick as Ferrari and Lewis (Hamilton) looked quick yesterday so it looks like we’ve got a bit of work to do.
"We are cracking exhausts and are having to change those every 150-200km. It’s a problem we can fix but here it’s difficult.
“We’ve got a handling imbalance because we are all learning about these tyres here and we’ve seen straight away some things we want done on the tyres which we’ll have done by Jerez.”
Schumacher was third fastest on both his days’ running - Monday and Wednesday - with Nico Rosberg fourth quickest on Tuesday.
Ferrari have been fastest on all three days - with Massa setting the pace on Monday and Tuesday before handing over to Alonso for the final day.
The Brazilian’s fastest lap was 0.3secs slower than Alonso’s.
Sauber have been the surprise package, with veteran De la Rosa second fastest on the first and third days and his Japanese team-mate Kamui Kobayashi occupying the same position on day two.
Sauber are back under the ownership of founder Peter Sauber after BMW, which had owned the team for the previous four years, decided to quit F1 following an uncompetitive season in 2009.
Button did not match the pace of team-mate Lewis Hamilton on Tuesday - but as they ran on different days no conclusions can be drawn about their relative performances.
Further down the order in terms of headline times were Renault, Williams and Toro Rosso.
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For them, Wednesday was a case of giving their more inexperienced drivers some miles.
At Williams, German novice Nico Hulkenberg took over from veteran Rubens Barrichello and set a best time of 1:13.699.
New Renault signing Russian Vitaly Petrov replaced number one driver Robert Kubica for his first experience of an F1 car.
He set a best time of 1:13.097, but that was at a stage when no other drivers were improving, so it suggests the team sent him out with low fuel.
And Jamie Alguersuari drove the new Toro Rosso, taking over from Sebastien Buemi managing a 1:12.576.