Ahead of today's all-important qualifying session the air temperature is 28 degrees C, whilst the track temperature is 34 degrees. Humidity is 76%.

Well, unless Paddy Lowe has had acting coaching from Robert de Niro or al Pacino, the fact is Mercedes is struggling here.

When the German outfit finished fourth and seventh on yesterday's timesheets we all assumed the team was struggling, but with Hamilton and Rosberg fourth and sixth this morning, both over a second off Sebastian Vettel's pace, it was clear there is a problem.

Rosberg admitted to going the wrong way with set-up yesterday, while Hamilton has been unhappy with balance and tyre degradation. Whether things will improve in the cooler temperatures this evening remains to be seen, but it certainly wasn't the case in FP2.

Indeed, all the Mercedes powered cars are struggling, other than the works cars the next best driver in FP3 was Valtteri Bottas, down in eleventh 1.9s off the pace.

Consequently, Ferrari, which looks very strong here, and Red Bull, hope to make hay while the moon is shining on the streets of Singapore.

As if to compound Mercedes issue here, seventh fastest this morning, just 0.014s off Rosberg's best, was Fernando Alonso in the McLaren. Even de Niro couldn't pull that one off.

Though they were unlikely to benefit from Mercedes problems, both Manor drivers have been hit with (5 place) grid penalties after changing the gearboxes on their cars.

The lights go green and Rossi leads the way, like his teammate he is already on the option rubber. Both Williams drivers on track, like the rest, on the prime rubber at this stage.

The Sauber duo are also on the option rubber, Ericsson looking good this morning.

As Maldonado runs wide in T7, a corner catching out almost everyone this weekend, Bottas gets proceedings underway with a 1:48.094. Moments later, teammate Massa goes second (48.300).

A big lock-up for Grosjean at T7, the Lotus looking a real handful.

Verstappen splits the Williams duo with a 48.159 but is demoted when Raikkonen goes quickest with a 47.077. Moments later, Ricciardo, despite a close encounter with the walls, posts 46.805.

A 47.571 sees Rosberg go third, the German understood to have revised his set-up (again) during the break.

Kvyat goes second with a 46.948 but all eyes are on Vettel who is quickest in the first two sectors. At the line the German posts 46.017, 0.788s quicker than second man Ricciardo.

Massa improves (48.112) but remains seventh, Raikkonen also improves, the finn going third with a 46.926.

Button goes fifth - yes fifth!!! - albeit on the option rubber. It's a move that will surely force some of the big guns - read Mercedes runners - to make the switch.

Clearly not content, Vettel posts a purple in the first sector, but loses time in the second. Pushing to the limit he loses time in S3 also, the Ferrari hampered by a slow Sauber.

As we predicted, drivers switch to the option rubber, amongst them the Mercedes duo, currently 6th (Rosberg) and 14th (Hamilton).

Currently, with 4:40 remaining, Sainz, Perez, Maldonado and the Manors comprise the drop zone.

Ricciardo and Raikkonen are back on track, the only drivers on the prime rubber.

Hulkenberg goes second (46.669), only to be demoted when Verstappen posts 46.483.

Kvyat goes quickest in S2 as Hamilton goes quickest overall with a 45.340. Rosberg can only manage fourth (46.201). Perez and Alonso sixth as Vettel is the only driver not on track.

Raikkonen, on track on primes, is down in thirteenth. Another mistake by Ferrari?

Despite a big lock-up at the Anderson Bridge, Massa goes quickest in S1. Elsewhere, Kvyat goes quickest (45.340). At the end of his lap, Massa can only manage thirteenth (46.879).

On the primes, Raikkonen improves to seventh with a 46.467, The Iceman still has it.

Bottas improves to sixth as Button makes a desperate late effort to escape the drop zone. Having posted PBs in the first two sectors, Button improves to fifteenth with a 46.891.

Quickest is Kvyat, ahead of Hamilton, Vettel, Ricciardo, Rosberg, Bottas, Sainz, Raikkonen, Verstappen and Perez.

We lose Nasr, Ericsson, Maldonado, Stevens and Rossi.