After a very brief pause to catch its breath following the drama of Brazil, Formula 1 has roared back into action in Spain this morning as preparations for 2009 get underway in earnest.
Most of the teams will be in action during this week's three-day Barcelona test, and the majority are expected to use hybrid cars featuring elements of the very different 2009 rules.
BMW Sauber was the first team to take to the track with a new-style wing package this morning, giving an early indication of what next season's cars might look like.
In a bid to improve overtaking, the 2009 machines will feature wider front wings and narrower rear wings - which should reduce the problems caused by aerodynamic turbulence from the rear of one car unbalancing the front of a chasing car.
The definitive 2009 cars will also feature much cleaner bodysides with most of the aerodynamic appendages between the wings now banned, Kinetic Energy Recovery Systems, and slick tyres.
Some teams plan either to try KERS systems this week, or simulate the additional weight involved, and Bridgestone has brought two choices of slick tyre compound.
As well as previewing how the cars might look in 2009, the test will also play a crucial role in shaping the final driver line-up, with shoot-outs for two of the remaining vacancies underway.
Former Honda and Super Aguri driver Takuma Sato is going head-to-head with GP2 driver and Red Bull protege Sebastien Buemi for the empty Toro Rosso seat - but both may yet have a shot at a race drive if the team chooses not to retain Sebastien Bourdais, who is testing alongside them.
Meanwhile Honda is evaluating GP2 front-runners Bruno Senna and Lucas di Grassi to see if either should replace Rubens Barrichello.
Should he not get the Honda drive, di Grassi could return to testing duties for Renault, where Dutch driver Giedo van der Garde (once a McLaren protege and Spyker test driver) is having a run this week as part of his prize for winning the Formula Renault 3.5 title.
Two much bigger names are also having F1 outings this week, with rallying legend Sebastien Loeb and MotoGP superstar Valentino Rossi appearing for Red Bull and Ferrari respectively.
Both are being rewarded for their 2008 successes, Loeb having clinched a record fifth World Rally Championship title this year and Rossi having returned to the top in MotoGP.
But while Loeb is testing alongside the F1 field at Catalunya, Rossi will get his Ferrari run in a private test at Mugello on Thursday and Friday.
Loeb and Rossi both have previous F1 testing experience - the rally ace have previously sampled an F1 Renault, and Rossi having tested extensively for Ferrari while pondering a career change in 2005 and 2006.