McLaren and Williams were the only teams in action at Jerez today, the penultimate day of testing for the 2009 season.

The Woking outfit's Heikki Kovalainen was the quicker of the two drivers on duty. Taking over from Lewis Hamilton, the Finn resumed the week-long programme of introducing and evaluating new aerodynamics modifications for the MP4-24.

In perfect weather conditions, the day proved productive, both in terms of evaluating the lap time potential of the new components and their effectiveness over the course of a simulated race stint.

The Woking team's pre-season preparations conclude tomorrow when Kovalainen will put the final pieces through their paces.

For Williams, who had Kazuki Nakajima on duty, the programme was all about the final preparations of the FW31, including set-up tuning, aero work, reliability checks and tyre testing. The Japanese driver completed 103 laps on his way to posting a best time 1.821s slower than Kovalainen.

"Kazuki spent our penultimate day working on mechanical set-up and signing off final components for the first race in Melbourne," said Sam Michael. "He'll be in the car again tomorrow for the final day of winter testing."

To check out our Jerez gallery, containing over 140 pictures, click here