Lewis Hamilton sets the pace in Chinese Grand Prix first practice

The McLaren driver set two fast laps at the end of the session to head Mercedes driver Nico Rosberg by a second at the top of the timesheets as a flurry of drivers set their best laps in the dying minutes of practice.

Hamilton, like team-mate Jenson Button, ran an upgrade package on his McLaren including modified front and rear wings and a new floor during the session - the team taking advantage of new-for-2012 regulations allowing sensor rigs to be run during Friday practice to measure the wake off the rear of the car.

Overnight rain meant that the 90-minute session started in damp conditions and during the half-an-hour most teams focused on installation laps and aerodynamic test runs.

Red Bull Racing's Mark Webber was the first driver to set a serious laptime, getting down to a 1m39.558s on the third flying lap of a six-lap run on Pirelli's medium compound rubber.

That lap was good enough to top the timesheets for much of the session as shortly after he had completed it, light rain made track conditions worse. By this stage, only nine drivers had completed serious runs and their laptimes were largely unchallenged until the track dried up enough for slicks to be run effectively in the final 10 minutes of the session.

Michael Schumacher had been in contention to top the timesheets after swapping fastest times with Webber with a few minutes to go, but he ended up third two-tenths behind his team-mate.

Behind him, the two Saubers of Sergio Perez and Kamui Kobayashi both improved at the eleventh hour as the track conditions rapidly improved, demoting Webber to sixth.

The Australian was running Red Bull's latest-specification exhaust setup, while team-mate Sebastian Vettel, who ended up one place and two-tenths behind him, used the exhaust setup the team ran early in testing to compare the performance of the two designs.

Button ended up eight fastest, complaining of traffic late on, with Scuderia Toro Rosso pairing Daniel Ricciardo and Jean-Eric Vergne rounding out the top 10, like most of the field setting their fastest times in the final few minutes on prime rubber.

All of the top 16 drivers improved late on, with Lotus driver Romain Grosjean down in 17th place the best of the drivers whose laps in the early dry phase of the session were not improved upon.

Force India reserve driver Jules Bianchi made his grand prix weekend debut as third driver at Force India, ending the morning in 20th place, setting his best time on intermediates unlike team-mate Nico Hulkenberg, who used medium slicks.

His opposite number at Caterham, Dutchman Giedo van der Garde, also made his first appearance, lapping around 1.5s off Heikki Kovalainen's pace.

Pos  Driver                Team                  Time               Laps
 1.  Lewis Hamilton        McLaren-Mercedes      1m37.106              7
 2.  Nico Rosberg          Mercedes              1m38.116s  + 1.010   14
 3.  Michael Schumacher    Mercedes              1m38.316s  + 1.210   14
 4.  Sergio Perez          Sauber-Ferrari        1m38.584s  + 1.478   13
 5.  Kamui Kobayashi       Sauber-Ferrari        1m38.911s  + 1.805   12
 6.  Mark Webber           Red Bull-Renault      1m38.977s  + 1.871   15
 7.  Sebastian Vettel      Red Bull-Renault      1m39.198s  + 2.092   12
 8.  Jenson Button         McLaren-Mercedes      1m39.199s  + 2.093    6
 9.  Daniel Ricciardo      Toro Rosso-Ferrari    1m39.748s  + 2.642   16
10.  Jean-Eric Vergne      Toro Rosso-Ferrari    1m39.768s  + 2.662   14
11.  Fernando Alonso       Ferrari               1m40.056s  + 2.950   14
12.  Felipe Massa          Ferrari               1m40.153s  + 3.047   14
13.  Valtteri Bottas       Williams-Renault      1m40.298s  + 3.192    8
14.  Nico Hulkenberg       Force India-Mercedes  1m40.328s  + 3.222   13
15.  Pastor Maldonado      Williams-Renault      1m40.540s  + 3.434   12
16.  Heikki Kovalainen     Caterham-Renault      1m41.071s  + 3.965   14
17.  Romain Grosjean       Lotus-Renault         1m41.204s  + 4.098   14
18.  Timo Glock            Marussia-Cosworth     1m42.330s  + 5.224   14
19.  Giedo van der Garde   Caterham-Renault      1m42.521s  + 5.415   11      
20.  Jules Bianchi         Force India-Mercedes  1m44.118s  + 7.012    8
21.  Pedro de la Rosa      HRT-Cosworth          1m44.227s  + 7.121   10
22.  Charles Pic           Marussia-Cosworth     1m44.500s  + 7.394   15
23.  Narain Karthikeyan    HRT-Cosworth          1m47.204s  + 10.098  12
24.  Kimi Raikkonen        Lotus-Renault         1m50.465s  + 13.359  11

All Timing Unofficial