After the two most diverse practice sessions of the year, which started off in twilight but ended in full darkness, Red Bull Racing's Sebastian Vettel set the quickest lap of the Singapore circuit so far this weekend with a lap of 1:46.374 in the second free practice session. Vettel beat his own fastest lap in free practice last year of 1:46.660.

The German - who has a chance of becoming the youngest-ever double world champion this weekend - used Pirelli's P Zero Red supersoft tyre to set his fastest time, which has been specifically developed to provide peak performance on tight and twisty street circuits such as Singapore. Despite ambient temperatures of 30 degrees centigrade or more, both the P Zero Red supersoft and the P Zero Yellow soft performed faultlessly in the hot and humid conditions. As well as targeting outright times, the drivers focussed on the performance of the tyres over long runs, accumulating vital data for the race.

The opening session, scheduled between 1800-1930 hrs, was shortened to an hour after it got away half an hour late due to track repairs. McLaren's Lewis Hamilton was quickest in the session with a time of 1:48.599, set in the closing minutes with the P Zero Yellow tyre, which was used by all the drivers in FP1.

The second session, held from 2130-2300 hrs, enabled teams to fine-tune the car set-up to the unique demands of Singapore, which provides a huge challenge for the cars, tyres and drivers. With 23 corners, the rear tyres are worked particularly hard as they constantly have to find traction on the bumpy surfaces. The tight confines of the track also caught out several drivers today. A problem for Jenson Button halfway through the second session meant that the Englishman was the only driver who did not get a chance to run on the P Zero Red supersoft so far.

All the drivers were allocated the usual three sets of tyres for Friday's free practice (two of P Zero Yellow and one set of P Zero Red). On average they completed between 10 to 12 laps using the soft tyre in the first session, and then 16 laps each on the soft and supersoft tyre in the second session, practising pitstops as they changed sets.

Paul Hembery: "This was one of the most important free practice sessions of the year for the teams, and the number of people encountering problems showed just how tough it was. Singapore is an extremely demanding track, so it was vital for the teams to assess the correct set-up, particularly on full fuel tanks, as this is a circuit that is particularly heavy on fuel consumption. Naturally, a heavy car works its tyres harder, but despite this factor and the warm conditions, we've been very pleased with the performance and durability of both our P Zero compounds. We've seen a difference of about a second per lap between the two compounds but with all the teams trying out different fuel loads, it's hard to get an exact picture until we've examined all the data."

Check out our Singapore practice gallery, here.