Ahead of today's sole free practice session, the air temperature is 21 degrees C, while the track temperature is 27 degrees. Once again it is bright and sunny. It's also worth pointing out that it's a sizeable crowd, loads of fans out there in the stands and in the various enclosures.

The lights go green, and Adrian Sutil leads the crocodile of cars at the end of the pitlane out on to the Barcelona track. Following its problems yesterday, McLaren will be hoping for an improvement today. Also, as we remarked at the time, BMW discovered that there was little to choose between the two tyre options (hard and medium).

Hopefully, this morning's session will give us a better idea of the true pecking order.

As the cars complete an installation lap before returning to the pits, it is Fernando Alonso, naturally, that receives the biggest welcome.

Having completed his installation lap, Hamilton is in no rush to get back to work. Having had a friendly chat with Norbert Haug and an engineers, the Englishman wanders over to the pit-wall to talk to Ron Dennis, who seems in an extremely good mood.

With ten minutes gone, eighteen cars have been out, but no times posted. Other than the buzz from the crowd, the track is silent.

Suddenly, an engine bursts into life, and moments later Jarno Trulli heads down the pitlane. The Italian posts the first time of the day, setting the benchmark at 1:24.638. Within minutes nine other cars are on track.

Fifteen minutes into the session, Raikkonen heads down the pitlane, leaving his teammate, Felipe Massa, as the only driver yet to make an appearance.

Heidfeld goes quickest (23.348), ahead of Bourdais, Kubica, Button and Trulli. However, Raikkonen is on his first flying lap of the day. Sure enough, the Finn crosses the line at 22.804, as Rosberg goes second, ahead of Bourdais and Vettel.

As Kovalainen goes quickest in the second sector, Hamilton heads down the pitlane. The Finn takes top spot (22.797) as Barrichello goes third. The crowd cheers Alonso who begins his first flying lap of the day. In his enthusiasm the Spaniard gets wildly out of shape.

Barrichello goes quickest and Alonso second, while Raikkonen and Kubica both leapfrog Kovalainen to go third and fourth. Hamilton goes eighth, but on his next lap goes quickest in the second sector, improving to third overall (22.503).

Replay shows Sutil getting out of shape and spinning as Massa goes eighth. While Barrichello remains quickest (22.460), Alonso and Hamilton both look set to improve. Sure enough, the Spaniard takes the top spot with a 22.271 as Hamilton remains third.

As Coulthard goes second (22.423), Piquet takes a detour across the tarmac run-off. Despite this however, the Brazilian posts a 22.544 to go fifth.

Coulthard goes quickest, the Scot posting 22.068, tantalisingly close to breaking the 1:21s barrier. Meanwhile, his Red Bull teammate, Mark Webber, remains the only driver yet to post a time. It would appear that the Milton Keynes outfit is still suffering reliability issues.

Bourdais goes quickest in the first sector, but then opts to dive into the pits. Meanwhile, like several before him, and Sutil just a few minutes ago, Coulthard gets out of shape and spins.

Barrichello goes quickest in the final sector, thereby improving to third overall. Meanwhile, all eyes are on Raikkonen, who is currently ninth.

As Glock improves to second (22.1545), Kovalainen goes eighth overall, having gone quickest in the first sector. Hamilton is also on track, as is Coulthard, who goes quickest in the second sector. The Scot (hards) crosses the line at 21.580 to consolidate his top spot, however, Bourdais (hards) is also on a hot lap. The Frenchman goes fifth, crossing the line at 22.320.

With thirteen minutes remaining, it's: Coulthard, Glock, Alonso, Massa, Bourdais, Barrichello, Raikkonen, Piquet, Vettel and Hamilton.

Rosberg complains of understeer, something which many drivers appear to be suffering this morning… as perfectly demonstrated by Vettel moments later and Barrichello shortly after that.

With just over seven minutes remaining, there are two cars on track - Kubica and Trulli. However, it's about to get very, very busy out there as the final assault begins.

One by one the others emerge, as Kubica (softs) goes second with a 21.717. Trulli takes third with a 21.860.

Heidfeld (hards) goes quickest in the first sector, setting a personal best in the second. He crosses the line at 21.269, clear proof that there isn't a major difference between the two compounds, at least not on the BMW, and not over one or two laps.