Ahead of today's opening session, the air temperature is 16 degrees C, while the track temperature is 26 degrees. It is bright and sunny.

Just 48-hours after the FIA's ruling, McLaren and Renault are scheduled to be introducing their 'double-decker' diffusers this weekend, while Ferrari has opted to drop its KERS systems for now just as Robert Kubica decides to finally try the device in anger.

McLaren is running a new front wing, however, only Lewis Hamilton has it. Indeed, the World Champion appears to be the only McLaren driver with the new diffuser. While this might frustrate teammate Heikki Kovalainen, it will offer us the opportunity to compare the two.

The other news today, is that Brawn GP has another new sponsor on board, M I G Investments is a leading Swiss Forex broker.

The tyre options on offer this weekend are medium and super-soft, a move that has not gone down well with Fernando Alonso.

"I think it is the worst decision they made in a long time," he told reporters yesterday, "it is a ridiculous tyre for here, for Shanghai.

"We will need to change the tyres after five or six laps," he added, "because this track is harder than Melbourne and there we only did eight or nine laps.

"I don't know if Bridgestone made the decision or the FIA, but they have to reconsider this type of decision because we look ridiculous on television and we look ridiculous for the spectators, and it is a joke to be in front of TV six seconds slower."

When the lights go green, Sutil is first out, followed by Vettel , Buemi, Piquet, Alonso and a whole host of others. Massa and Button are among the early risers, the Brazilian getting very much out of shape as he heads back into the pits.

Barrichello goes out for his installation lap and seven minutes into the session all but Heidfeld and Glock have been out.

Sixteen minutes into the session, with Heidfeld and Glock both having been out for their installation laps, Hamilton follows Sebastien Buemi down the pitlane, the first drivers to make a second run, then again, the Englishman and his team have a lot of testing to carry out today. Engine rules permitting.

While Sebastien posts a 41.316, Hamilton crosses the line in 55.796. The Englishman is told to discharge his KERS on the back straight and also try his adjustable front wings. Buemi improves with a 39.959 and Hamilton 46.814, as Nakajima splits them with a 42.651.

Raikkonen goes third with a 43.630 having gone wide at Turn 15, as Nakajima improves with a 39.976.

As Raikkonen improves to 39.532, Massa heads down the pitlane weaving left and right as he generates heat into his tyres. Something you rarely see in the pitlane.

Jarno Trulli goes quickest with a 39.269, but this is soon beaten by Raikkonen who posts 38.530. However, next time around the Italian re-takes the top spot with a 37.945.

As Massa goes third with a 38.555, Trulli slowly heads back to the pits, "I have a problem," he tells his crew, "I don't know what it is, but I have no lights on the steering wheel".

As Vettel begins his first flying lap, Massa improves with a 38.418, but remains second to Trulli. Moments later, Rosberg takes second with a 38.174, as Trulli finally arrives back at his garage.

Massa's car still extremely 'skittish', as Glock goes fifth, ahead of Vettel, Bourdais and Alonso. "I've got a bit of graining," Massa tells his crew, "I'm losing grip!".

Rosberg, Alonso and Hamilton all on hot laps, going quickest in various sectors. The Spaniard goes third with a 38.089, as Rosberg improves with a 37.860. Hamilton crosses the line at 38.316 while Webber takes fifth with a 38.111.

Hamilton improves to sixth with a 38.270, as Kovalainen, sans new diffuser and front wing, takes third with a 38.027.

As Hamilton takes top spot with a 37.603, ahead of Webber, both Brawn cars are on track. Glock goes quickest in the second sector, but then has a massive lock-up at Turn 11.

Coming up to half-time, Button goes sixth and Barrichello seventh, the Brawn duo just 0.004s apart.