Lewis Hamilton underlined the claim that a dodgy set-up had hampered his attempts to win the Japanese Grand Prix a week ago by returning to the top of the timesheets in opening practice in Korea.
The Briton qualified poorly at Suzuka and was only able to rise to fifth place in the race, but this week confirmed that a failure in his rear suspension had been at the root of his problems, and showed that McLaren could again be a factor in this weekend's event by the field with points leader Fernando Alonso.
Hamilton was among the early pacesetters as McLaren defied a dusty circuit to work on the development of the MP4-27, but it was only after he was told by his team that no-one appeared to be going faster than their initial times that he moved back ahead of Alonso, who had set a blistering pace in his Ferrari. Having trailed the Spaniard by a couple of hundredths heading into the final few minutes, Hamilton produced two faster laps that eventually left him three-tenths clear at the front of the pack.
Having been denied the chance to show what he could do in the race at Suzuka, Alonso wasted little time in emphasising that he will not just roll over in this year's championship battle, joining team-mate Felipe Massa and the McLaren drivers at the top of the times. The Spaniard's bid to keep Hamilton at bay, however, ended with a massive lock-up in the closing stages which left the F2012 with serious vibration problems and eventually prompted Alonso to return to the pits.
Massa was denied third spot after Mark Webber put in a late run that saw him edge the Brazilian by a couple of tenths, with the second Red Bull of Japanese GP winner Sebastian Vettel in fifth spot, just ahead of Michael Schumacher. The German, who retires at the end of the season, was closely followed by Mercedes team-mate Nico Rosberg, who admitted in the build-up to the event that he felt the Korean circuit would suit the W03 better than Suzuka had.
Romain Grosjean, having escaped a ban for his collision with Webber at the start a week ago, was eighth fastest in the best of the Lotus entries, with Paul di Resta and Button rounding out the top ten.
With the exception of the dust, which made finding the limits more difficult than usual on the seldom-used circuit, there were few problems during the 90 minutes, although Marussia's Timo Glock lost time early on as he pitted for a steering rack change after just one lap. Sergio Perez was among those to explore more than the limits of the circuit, taking to the run-off more than most, and the Mexican finished down in 15th spot, one behind Sauber team-mate Kamui Kobayashi, with Kimi Raikkonen, Pastor Maldonado and Force India reserve Jules Bianchi all quicker than both Swiss cars.
Behind Perez, the field looked very familiar, with the Toro Rossos of Daniel Ricciardo and Jean-Eric Vergne next up, but only just ahead of Williams reserve Valtteri Bottas, Caterham's Heikki Kovalainen and Glock, who managed to get 13 laps in towards the end of the session. Charles Pic was half a second slower than his team-mate, with the second Caterham of Giedo van der Garde all but matching the Frenchman. HRT, meanwhile, brought up the rear, with Pedro de la Rosa nearly two seconds off the Dutchman and Dani Clos another 1.2secs behind as he returned to the cockpit of Narain Karthikeyan's usual mount.