Jenson Button set the fastest time for the third practice session in a row at the Japanese Grand Prix, with a lap over half a second clear of the rest of the field.
Button's time of 1:31.255 was the fastest of the weekend, and 0.507s up on team-mate Lewis Hamilton as the drivers prepared for the afternoon's qualifying session. Red Bull is either very confident in their pace or slightly struggling, as Sebastian Vettel could only manage a 1:32.122 for third and Mark Webber was back in fifth, over a second off Button's pace.
However, both Red Bulls looked as though they were on heavy fuel loads, with the car less willing to turn into the fast Esses at the start of the lap. Fernando Alonso was also in the mix in fourth place, but over a second off Button's time, while the second Ferrari of Felipe Massa was just about on the pace in sixth.
Despite setting the quickest time of the session, Button was not entirely happy with his car and got out with five minutes remaining so the team could make some last-minute setup tweaks. He completed just 13 laps in total - less than any of the other car in the top ten, including Webber who spent the first half of the session in the pits with an engine problem.
The two Mercedes resumed their usual position in seventh and eighth, with Michael Schumacher leading Nico Rosberg after both cars set their soft tyre laps relatively early in the session. Vitaly Petrov was ninth in the Renault, but his team-mate Bruno Senna was back in 17th after a big shunt on his sixth lap.
Senna lost the rear of his car exiting Spoon and was spat into the nearside tyre barrier, which ripped the front-left wheel off its suspension. His team will have a tough job getting the car ready for the start of qualifying and will be hoping there is no damage to the main tub.
Adrian Sutil rounded out the top ten in Senna's absence, while the Toro Rossos remain a contender for the top ten in qualifying. Williams' struggles continued but the team did complete 39 laps between the two cars, which was nearly as much as they managed over both 90 minute sessions on Friday.
Tonio Liuzzi's bad luck did not change however, as he was forced to pull over in his HRT for the second session in a row. He has competed just 12 laps of the circuit ahead of qualifying.