Marc would continue his testing by setting the fastest time of the day while testing in preparation for the Canadian Grand Prix. Marc would set a time of 1m:22.632, completing seventy eight laps. This day would see Marc up against Ferrari's Rubens Barrichello, who was driving the F2003-GA. Marc would be three tenths of a second faster.

The day would focus mainly on tyre testing, with Marc running a race simulation, which was cut short due to technical problems.

At Silverstone Ralf focused on the set-up of the chassis and tyres. He would finish the day with a best lap time of 1m:23.495, completing sixty laps.

Sam Michael, WilliamsF1 Chief Operations Engineer, commented on the Silverstone test by saying: "Once again, intermittent showers hampered the testing schedule but Ralf managed to complete 60 laps. We continued with yesterday’s programme of mechanical set up work, which included engine reliability running and tyre testing for Michelin and we are fairly happy with the progress made."

Tim Newton, WilliamsF1 Test Team Manager, was at Monza: "We had another successful day at Monza today with Marc completing 78 laps in the FW25. As with the test running at Silverstone, our primary focus was establishing optimum set-up options for the forthcoming Canadian Grand Prix whilst also concentrating on engine work and tyre performance."

Silverstone Times:

Driver Car / Engine Best Time Laps

C da Matta Toyota 1:22.382 76
R Schumacher WilliamsF1 BMW 1:23.495 60
R Firman Jordan Ford 1:23.595 21
G Fisichella Jordan Ford 1:24.633 42

Monza Times:

Driver Car / Engine Best Time Laps

R Barrichello Ferrari 1:22.584 59
M Gene WilliamsF1 BMW 1:22.631 78
F Massa Ferrari 1:23.283 64
H H Frentzen Sauber Petronas 1:23.359 77
A Davidson B.A.R Honda 1:23.492 39
O Panis Toyota 1:23.56 93
P de la Rosa McLaren Mercedes 1:23.617 89
T Sato B.A.R Honda 1:23.93 51
J Villeneuve B.A.R Honda 1:24.10 43