Ahead of today's opening session - the first of the season - the air temperature is 21 degrees C and the track temperature is 22 degrees.

The session begins at 12:30 (local time) and while the track had almost dried out following overnight rain there was another brief shower around half-an-hour ago. Five minutes before the start there are a few more drops of rain in the air. "Track conditions will not be great at the beginning," admit Ferrari.

All twenty-four drivers should be taking part this morning, HRT having passed scrutineering and the parts needed for Pedro de la Rosa's car arriving at the eleventh hour.

As we await the pitlane lights to give the go, there is a horrendous oil patch on the track between turns 3 and 4, courtesy of one of the support races. The session is declared wet.

The lights finally go green and after a short wait Vergne gets things going, the Toro Rosso shod with inters. Shortly after, he is followed by Ricciardo, Maldonado, Glock, Senna and local hero Webber.

It might be a new season, but the timing screens are playing up as usual, numbers giving way to hieroglyphics.

More and more drivers pour on to the track, some, noticeably Rosberg, opting for full wets.

Seven minutes into the session all but Schumacher and de la Rosa have been out. Replay shows Rosberg running wide between turns 11 and 12. The German and Massa are the only drivers to have completed two laps however, nobody has posted a time as yet.

As one would expect, drivers are complaining of low grip. Then again, when was the last time a driver complained of too much grip?

Sixteen minutes into the session, after almost ten minutes of total inactivity, Ricciardo heads down the pitlane. Still no sign of de la Rosa coming out.

As Ricciardo begins another lap, he is joined by Massa, Vergne and Vettel.

The Australian crosses the line at 1:47.448 to post the first time of what will be a long, long season.

As Ricciardo improves with a 42.490, Vettel goes second with a 44.870. Moments later the German has a huge wobble.

Vergne goes quickest (41.629) but is quickly leapfrogged by his teammate's 41.001, Vettel heads back to the pits. Schumacher waits impatiently in the Mercedes garage.

As the Toro Rosso duo trade best laps, Alonso goes quickest in S1 and S3, crossing the line at 37.941 to take the top spot.

Not for the first time there's a problem for HRT, Karthikeyan crawling around the back of the circuit with what is clearly an engine problem. Engine problem as in "no power".

Rosberg goes second (39.744), only to be demoted by Webber (38.421), Ricciardo remains fourth, ahead of Vergne, Vettel and Kobayashi.

Next time around, Rosberg goes quickest the German posting a 37.147. Countryman Hulkenberg, on his first lap, goes seventh with a 42.037.

Pic's first lap is a full 25s off the pace, while Kobayashi takes the top spot with a 36.906.

In the Lotus garage the crew is working furiously on Raikkonen's car, removing the entire steering column. The Finn is one of 13 drivers yet to post a time.

Approaching halftime, Pirelli believes it wont be too long before the slick tyres make an appearance. The two compounds this weekend are medium and soft.

At halftime, it's: Kobayashi, Rosberg, Alonso, Webber, Senna, di Resta, Ricciardo, Hulkenberg, Vergne, Vettel and Pic. Indeed, these are the only drivers to have posted times.

Karthikeyan's problem was due to the engine temperature rising and then cutting out as a safety measure.

Perez is the first driver to make the switch to slick rubber, the Mexican returning to the pits after just one lap.