After weeks of relative silence the sound of F1 engines reverberated for the first time today in earnest as testing got underway at the Algarve circuit.
In a mix of old and new it was Sebastien Buemi in last year's Toro Rosso who set the pace in the rather wet conditions.
The rain hampered play for part of the day with a heavy downpour in the afternoon curtailing the running.
However, the wet weather didn't stop Buemi who completed 65 laps in the STR3, clocking a best time of 1:41.528.
That put the Swiss driver almost five seconds ahead of second placed Pedro de la Rosa.
The Spaniard drove an interim McLaren MP4-24, which at various stages of the day was fitted with either the new 2009 front wing and last year's rear or an old front and a new rear.
Meanwhile Nico Hulkenberg, putting the new Williams FW31 through its paces for the first time, posted the third fastest time, a quarter of a second off de la Rosa's pace.
However, the German's first run wasn't without problems as he aquaplaned off the track, damaging the front nose of the newly-launched car.
Nelson Piquet Jr, also driving his team's 2009 challenger for the first time, finished in fourth place ahead of Toyota test driver Kamui Kobayashi.
"Today has gone well and I am happy with the new car," said Kobayashi, who previously tested the car on Sunday.
"It has been an interesting experience to drive with KERS for the first time and we are understanding more about the system all the time.
"This is my first time driving at this track and I have to say I am very impressed; the lay-out is really exciting and quite challenging for a driver.
"The weather was far from ideal, especially in the afternoon, so that meant we could not spend as much time on track as we planned."
1 S. Buemi Scuderia Toro Rosso 1:41.528 65 laps
2 P. de la Rosa McLaren 1:46.076 28 laps
3 N. Hulkenberg Williams 1:46.335 28 laps
4 N. Piquet jr. Renault 1:48.989 33 laps
5 K. Kobayashi Toyota 1:50.989 46 laps
source : Planet F1