Hamilton fastest on day one at Monza

The McLaren driver, who was trying out a new ultra low-downforce wing package, set a best lap of 1:24.112 seconds on a day that was blighted by a late rain shower. He was briefly delayed by a CV join failure during the morning, but was soon able to return to the track.

Ferrari have been working on improving their F2007 in its handling of kerbs and Raikkonen seemed fairly happy with the pace of his car as he too worked on the team's high-speed aero solution.

Nick Heidfeld proved that BMW Sauber's confidence for Monza was well placed as he set a third quickest time less than two tenths of a second behind Hamilton.

Jarno Trulli was fourth quickest for Toyota, who were trying out their new low-downforce configuration. This includes a new rear wing and sidepods.

Kazuki Nakajima was drafted in for the first day by Williams, with the Japanese racer aiming to impress the team as he looks for options in Formula One next year. He too tried out aero solutions that included a McLaren-style bridge wing over the nose.

Sebastian Vettel showed stronger than usual pace for Scuderia Toro Rosso to end the day sixth quickest, while Nelson Piquet Jr carried out Renault's first proper track test with the controversial 2008 standard ECU.

Rubens Barrichello was eighth quickest for Honda Racing, while Red Bull Racing's Mark Webber had another frustrating day as he ended it ninth overall and also suffered a mechanical problem in the afternoon that brought out a red flag.

Super Aguri test driver James Rossiter also brought a red flag out in the morning, after suffering an electrical glitch on his steering wheel. He ended the day 10th overall.

With the rain arriving just before the end of the session, teams are already making preparations to stay on for an extra day on Friday if it is wet tomorrow.

Pos  Driver       Car                      Time      Laps
 1.  Hamilton     McLaren-Mercedes    (B)  1:24.112  53
 2.  Raikkonen    Ferrari             (B)  1:24.258  60
 3.  Heidfeld     BMW-Sauber          (B)  1:24.277  76
 4.  Trulli       Toyota              (B)  1:24.523  61
 5.  Nakajima     Williams-Toyota     (B)  1:24.653  98
 6.  Vettel       Toro Rosso-Ferrari  (B)  1:25.106  63
 7.  Piquet       Renault             (B)  1:25.366  94
 8.  Barrichello  Honda               (B)  1:25.377  83
 9.  Webber       Red Bull-Renault    (B)  1:25.427  61
10.  Rossiter     Super Aguri-Honda   (B)  1:25.548  64