Ahead of today's all-important qualifying session the air temperature is 19 degrees C, whilst the track temperature is 29 degrees. It is bright but with a fair amount of cloud. There is a 20 percent chance of rain.

We say 'all important' because this is, after all, Monaco, and you'll be aware of all the comments such as 'like flying a helicopter in your living room'. Overtaking isn't impossible here, but it's not easy, therefore why not make things a little easier on yourself by trying to start as far up the grid as possible... we're talking to you Kimi.

Whilst Lewis Hamilton was the pace-setter in Thursday's session and looked set to make it a hat-trick this morning, Sebastian Vettel turned everything on its head when he put in a sensational lap, out-acing the Briton by 0.562s - Nico Rosberg splitting the pair.

Hamilton might have been able to improve, but serious traffic on his final flying lap put paid to that.

Kimi Raikkonen was also looking good until a mistake at Ste Devote saw the Finn bring out the red flag, whilst Max Verstappen had a misunderstanding with the barriers at Anthony Noghes later in the session.

The Red Bulls look much improved here, while the Toro Rosso pair continue to amaze however, both Williams were woefully off the pace suggesting that either they were continuing their set-up work from Thursday or have a major problem here.

Taking eighth earlier, Jenson Button has perhaps given McLaren hope on a track which has seen so many successes for the Woking outfit... and its engine partner.

Force India has also shown signs of improvement whilst Sauber struggled.

Remember... nine of the last ten winners started from pole.

The lights go green and Stevens leads the way, followed by most of the field including the Mercedes duo... clearly everyone is taking the threat or rain - albeit 20% - quite seriously. All but Stevens, Merhi and the Saubers are on primes.

With 17 drivers on track, traffic is a nightmare... as ever. Perez, Hulkenberg and Alonso remain in their garages.

Stevens posts 25.869 but Verstappen almost immediately posts a far more sensible 19.803.

Having found himself a little bit of breathing space Vettel goes quickest with an 18.323, however, Rosberg (17.463) and then Hamilton (16.884) go quicker.

Next time around, Vettel and Rosberg improve but not enough to leapfrog Hamilton who ups the ante with a 16.588.

On the option rubber, and thereby forcing the opposition's hand, Nasr goes fourth with an 18.101. Raikkonen is currently ninth (18.633).

Rosberg improves with a 16.528, 0.060s quicker than his teammate, whilst a 17.502 sees Raikkonen go fourth.

Hulkenberg currently sixth, ahead of Verstappen, Ricciardo,, Maldonado and Kvyat.

Perez and the McLaren duo are currently in the drop zone with the Manors.

Hulkenberg says he has hit the wall at Turn 5 (Mirabeau) and will have to pit.

Alonso goes tenth (18.304) having lost a heap of time behind a very slow Grosjean at Rascasse.

Perez (options) goes third (17.376), which, with 3:19 remaining, could cause problems.

Sainz is under investigation for missing the weighbridge.

Williams woes continue, as Massa can only manage eleventh and Bottas seventeenth.

Button (options) improves to seventh thereby dropping Raikkonen to tenth.

A late improvement to fourteenth for Hulkenberg which drops Nasr into the drop zone.

Bottas backs off allowing his teammate through. Massa goes twelfth (17.679), whilst the Finn peels off into the pits having failed to make the cut.

Quickest is Rosberg, ahead of Hamilton, Verstappen, Kvyat, Sainz, Ricciardo, Perez, Button, Vettel and Hulkenberg. Both Ferraris through, and, like the Mercedes pair, not needing to use the softer rubber.

We lose Nasr, Bottas, Ericsson, Stevens and Merhi.