Warm-up: Rain. Lots of it...

The Capello/Kristensen works R8 headed the session, with the sister car of Frank Biela and points leader Emanuele Pirro second. Third, and confirming its status as dark horse, was the Champion-run R8 of Andy Wallace and Johnny Herbert.

Atrocious track conditions at Road Atlanta meant times were some 12 seconds down on a reasonable race pace, but the forecast is that rain should clear from the area an hour before the noon start (17:00 BST). Nevertheless, the teams expect conditions to be at least partly damp for the opening stages of the 1000km/10-hour race.

Best non-Audi was the Panoz LMP1 of Jan Magnussen and David Brabham, with the fourth and final Audi - the older-spec Gulf car of Stefan Johansson and Patrick Lemarie - fifth. The second Panoz of Graf and Lagorce completed the top six.

Behind the 'big two' marques, the conditions allowed several interlopers to mix it with the LMP900 ranks. Seventh was the highest-placed LMP675 machine, the Gene/Schroeder/Deletraz Reynard 2KQ, with the GTS Viper of Hezemans/Kumpen in eighth.

Prodrive's Ferrari 550 Maranello made its mark too, the Rydell/Kox/Duex machine taking ninth overall.