After a four-week summer break, the Formula One field returned to action in the majestic setting of Spa: one of the most challenging tracks of the year that is characterised by a long lap and uncertain weather.

This was the case once more this year, with rain dominating the first free practice session in the morning after only 10 minutes of dry running. On the 20th anniversary of his Formula One debut in Belgium, Michael Schumacher set the fastest time for Mercedes in the opening session, with a time of 1:54.355, having managed to post a benchmark on the P Zero White medium tyres before the rain fell. His team mate Nico Rosberg was second-fastest under similar circumstances, with both Mercedes nearly half a second quicker than their rivals.

Rain then fell for the rest of the session, giving the drivers the chance to accumulate plenty of information about the P Zero Orange wet tyre and the P Zero Blue intermediate tyre, which are likely to see lots of action over the rest of the weekend.

The rain held off at the start of the afternoon session but the standing water that remained meant that all the drivers started off with intermediate tyres. Once the crossover point had been reached - the time at which it becomes quicker to use slick tyres rather than intermediates - Fernando Alonso set the pace on the P Zero Yellow soft tyres, before being beaten by Red Bull Racing's Mark Webber on the same tyres, who posted a time of 1:50.321.

Conditions then became wetter once more, with many teams electing not to run during the final half-hour of practice today, having accumulated enough wet weather running in the morning. With the teams now allocated four sets of intermediate tyres and three sets of wet tyres for the weekend, and a high likelihood of further bad weather, the emphasis was on conserving the tyres for the remaining days - although one set of the intermediate tyres has to be returned at the end of Friday.

Paul Hembery: "First of all, it's great to be back on track again after the summer break, and there are few more spectacular places to return to action than Spa. Today we saw a typical day at Spa-Francorchamps, which was all about the Belgian weather. Conditions were extremely variable, with differing amounts of water in different places on the track. This gave the teams the opportunity to assess both the slick, wet and intermediate tyres over a wide window of parameters and conditions. Being the longest lap of the year, tyre strategy will be more important than ever this weekend, with a difference of about 1.2 seconds per lap predicted between the P Zero White medium and P Zero Yellow soft tyre - in dry conditions. But the weather here is incredibly hard to predict, which means that all the data accumulated on the wet and intermediate tyres this weekend is sure to be very useful as well."

To check out our Spa practice gallery, click here.