Lewis Hamilton showcased McLaren's ability to produce developments for its cars by vaulting the MP4-24 from the lower reaches of the timesheets to top spot in free practice at the Chinese Grand Prix.
While the overnight improvement will be taken with a pinch of salt at this point in the weekend, as other teams work through their own programmes, Hamilton made the most of a car fitted with a revised front wing and diffuser to head the hitherto unbeaten Brawns of Jenson Button and Rubens Barrichello at the end of the opening 90 minutes of track time in Shanghai.
The world champion clocked a 1min 37.334secs lap to head the times by just over a tenth of a second, while McLaren's general improvement was highlighted by the presence of team-mate Heikki Kovalainen in fourth place, despite the Finn's car appearing to run a set-up more akin to those seen in both Melbourne and Malaysia. Kovalainen ended the session 0.338secs shy of Hamilton, completing a 'Brawn sandwich'.
Mark Webber confirmed Red Bull's claim to be the best of the non-diffuser teams prior to Shanghai, pushing the best of the RB5s into fifth spot, ahead of expected frontrunners Jarno Trulli and Nico Rosberg - the German for once not at the top of the times in his Williams. Timo Glock, Fernando Alonso and the surprising Sebastien Bourdais rounded out the top ten.
There was trouble for Toyota, however, as Trulli, having moved into an early lead on the timesheets, was reduced to a crawl by a suspected hydraulics problem. The Italian returned to the track later in the session, however, completing a respectable 19 laps, a figure comparable to many in the field. Sebastien Buemi, learning the circuit in an F1 car, completed a session-high 26 tours, with Kazuki Nakajima next up on 25, although the pair ended the session 13th and 19th respectively.
Ferrari, too, struggled for respectability, the decision to ditch its KERS system maybe having a knock-on effect on overall pace. Kimi Raikkonen wound up eleventh fastest, with Felipe Massa, his F60 making life hard for its tyres, was only 15th, behind Buemi and the Force India of Adrian Sutil.
BMW Sauber was also at the 'wrong' end of the times but, as Sepang showed, the result may have had more to do with its focus on raceday rather than any outright lack of performance. Robert Kubica, 18th overall, was due to have evaluated KERS on his F1.09 for the first time.
The session got off to a slow start, with very few cars completing flying laps early on, and was also notable for the comparative lack of action on the supersoft Bridgestone rubber that has caused concern in the build-up to the event. Most drivers completed little more than an installation lap on the green-striped compound, preferring instead to make use of the harder 'medium' compound as temperatures hovered around the 18-degree mark.