Nico Rosberg posted the fastest time today at Barcelona for Mercedes as the final pre-season test for F1 2010 moved into its penultimate day.
Rosberg's best effort was a 1 minute 20.686 seconds, which left him more than seven tenths up on his closest rival. In the end the German did almost 600 kilometres - 128 laps, the most of anyone runner - despite intermittent rain throughout the morning.
He spent the day working on qualifying simulations and developing the cars set-up before completing a race simulation exercise in the afternoon. Rosberg's team-mate, record-breaking multiple F1 world champion Michael Schumacher will now take over the MGP W01 tomorrow for the fourth and final day.
"We had a good day today and made some significant progress in terms of set-up which was nice to see," said Rosberg. "We hadn't got the most out of the car in terms of performance over the last couple of days, but we made a step in the right direction today.
"We went through some big changes this morning step by step and found some good improvements. The longer runs this afternoon were interesting. We learnt a lot as there were other cars running similar programmes at the same time so we were able to do some comparisons. There is still plenty of room to improve but overall we're looking in pretty good shape."
Sebastien Buemi meanwhile was second and 'best of the rest' in his Toro Rosso STR5. It was his first day in action after Jaime Alguersuari ran on days one and two, and even though conditions were mixed he was happy.
"Despite the rain, my first day in Barcelona has gone well," said Buemi. "Carrying out a race simulation was very useful and it was particularly interesting to see how the tyre behaviour changed depending on the fuel load. In the races, it will be important to drive smoothly, as on full tanks it is very easy to damage the tyres if you slide too much. Today was good and so we can try and improve a bit more tomorrow, our last chance before Bahrain."
Jenson Button was next up for McLaren, just four hundredths off Buemi, on a 1m 21.450s. He opted to do a number of short installation runs this morning due to the weather, before completing a race simulation in the afternoon. Button will be replaced by Lewis Hamilton for day four.
Further down the order Rubens Barrichello and Felipe Massa came in fourth and fifth respectively, the former maintaining the promise shown by his Williams team-mate Nico Hulkenberg on Thursday and Friday. Hulkenberg was of course quickest on day two, and second on day one.