Decoding Jerez - Button tops times, but it's all to play for

After a rainy first couple of days, the second Jerez test actually turned out to be quite revealing and a picture has emerged of how the teams line up with the new season now less than a month away.

So far most of the testing has been reliability based, with some performance work this week by the more advanced teams. Next week's final test in Barcelona will be more about performance and many teams will bring major updates to their cars in preparation for the first race. From what we saw this week, the field is close enough for this to change the order, if someone finds a significant aerodynamic step. It is all to play for.

Jenson Button set the fastest time of the test on Saturday morning, a 1m18.871 on the first lap of a two lap run. The second lap was almost a second slower, most of the time being lost in the final sector of the second lap, presumably as the tyres started to go off.

"It's gone very well here, a great result for me and McLaren," said Button. At the moment the MP4-25 is good on the single lap, but we are also getting there on the long runs. We still have a lot to learn about the car on full tanks."

Fernando Alonso did not go for a low fuel short run in the Ferrari and set a time half a second slower than Button on the second lap of a 13 lap run. Once again the Ferrari's characteristic of suffering a long period of drop off on the tyres was evident.

However Alonso did a run starting in the 1m 21s on which he must have had 80 kilos to cover the laps he did. Fuel corrected this means he was lapping at around 1m18.9, so very close to Button's time.

At the end of the day Alonso did a 48 lap partial race simulation, with a pit stop on lap 13. The 35 lap run which then followed was very fast and consistent, laps in the 1m 22s moving into the 1m21s as the fuel burned off.

Engineers tell me that the established teams are covered by no more than 7/10ths of a second. Ferrari and McLaren are close but Ferrari has so far been more reliable. Red Bull follow. They don't seem to have the advantage I expected them to have, given where they finished last season and it will be interesting to see what new parts they bring next week and where they end up. Mercedes are in pursuit as well, as are Force India.

Renault looked more competitive on Saturday, with a 24 lap run in the low 1m 21s and high 1m 20s and a fastest time set on the second lap of a seven lap run.

Williams are more difficult to judge as they have done predominantly long runs with heavy fuel and have been putting the new Cosworth engine through exhaustive reliability runs, which make it hard to judge their true pace. But presuming that they have been quite conservative so far, they look like they could be in reasonable shape come the first race weekend.

Alonso gave some very bullish quotes about the Ferrari car to the media yesterday, which have raised the stakes quite a bit.

"This is the best car I've ever had," he said. "Red Bull, McLaren and Renault have been very quick and have shown their cards, while we are still hiding ours. We will analyse the data, but we are very optimistic. If I were in a different team I would be looking at Ferrari because everything is going really well.

"Maybe where Ferrari has to improve is the short runs with little fuel onboard."

He's being a little disingenuous here as the Ferrari looks pretty impressive on the first lap, it's just that they haven't been doing short low-fuel runs.

As it looks increasingly likely that teams are looking to run predominantly one stop strategies with one very long stint, Bridgestone are likely to err on the side of caution - they have always been a very conservative company and this is their final year in the sport - and bring tyres to races which are not marginal to allow for this kind of strategy.

Being able to qualify on the harder of the two tyres will be an advantage and it looks like the Ferrari and the McLaren can switch the tyres on over a single lap.