Jenson Button and Lewis Hamilton put their revised McLarens at the very top of the timesheets in the opening practice session for this weekend's German Grand Prix but, with rain again interrupting running, the true picture remains unclear.
The 90-minute session was blighted by squally showers that made it tricky to remain on slick tyres, and saw almost every driver suffer an off-track moment at some point, although the only serious damage occurred right at the end when Williams rookie Valtteri Bottas lost it as Sachskurve and rear-ended the tyre barrier.
Button's 1min 16.595secs benchmark - set in an MP4-27 fitted with revised rear bodywork, sidepods and exhaust exits - was around half-a-second quicker than his team-mate's best, but came early on, when the track was at its driest. With the rain making the middle third largely irrelevant in terms of times, Button was only likely to come under threat towards the end, when the surface began to run quicker again. Hamilton led the pursuit, although several drivers also closed the one-second gap that had previously existed, with Fernando Alonso eventually claiming third spot ahead of Michael Schumacher and Sergio Perez.
The Mexican was the final driver within a second of the pace, but was closely followed by Nico Hulkenberg, who had fellow German Nico Rosberg and Felipe Massa a short distance behind. Pastor Maldonado and Romain Grosjean rounded out the top ten.
The Frenchman did not run with the latest Lotus development parts, which were evident on the airbox of team-mate Kimi Raikkonen's E20, along with minor additions to the rear wing, suggesting the Enstone team has developed its own means of boosting its DRS capability. Raikkonen only completed 14 laps, and trailed Grosjean in 15th place, some two seconds off Button's pace.
Between the two Lotus drivers sat Kamui Kobayashi, Sebastian Vettel, Bottas and Daniel Ricciardo, with the world champion - who featured a new all-gold helmet to mark his home race - being joined by Silverstone winner Mark Webber in the bottom half of the field as Red Bull played itself in slowly.
Bottas was joined by fellow 'third drivers' Jules Bianchi and Dani Clos, who finished 16th and 24th respectively as they replaced Paul di Resta and Narain Karthikeyan at Force India and HRT.