Nico Rosberg led a Mercedes 1-2 in the first of the weekend's practice sessions at the Brazilian Grand Prix, but the conditions precluded any meaningful conclusions from being drawn.

The 90-minute session started damp, got wetter, dried slightly and then got wet again, meaning that little will be drawn from the times posted, while Pirelli will have got precious little information on next year's tyres, after grooved rubber was the order of the day.

Fortunately for the hardy souls looking on from the grandstands and grass banks, the threat of similar conditions over the weekend ensured that the teams had to take to the track and, after varied amounts of running, it was Nico Rosberg who wound up fastest of all for Mercedes.

Related Articles

The German, who moved to the head of the list early on, posted a target time of 1min 24.781secs, leaving himself nearly half a second clear of the field, which was headed by Mercedes team-mate Lewis Hamilton.

Hamilton underlined just how tricky the conditions were by spinning in the first half of the session, his W04 sliding sideways for some distance despite still being on the tarmac. Luckily, traffic was sparse as he attempted to three-point turn his way back into action, and he was able to improve his time later in the morning.

Ominously, Sebastian Vettel sat just behind the two Silver Arrows, despite Red Bull more intent on collecting data for 2014 as both its RB9s ran with a host of data-collecting sensors and gauges. The four-time world champion was also caught out by the track conditions, taking to the grass in the final moments, but there was no harm done as he headed team-mate Mark Webber by three places.

Between them, Jenson Button again gave McLaren early hope, claiming fourth spot on a weekend where he has vowed to end the season on the podium. The Briton was only a tenth off Hamilton and closer still to Vettel, while team-mate Sergio Perez put the sister MP4-28 seventh overall.

Fernando Alonso, who topped last weekend's opening session in Texas despite a bad back, was fifth overall on this occasion, while rookie Daniil Kvyat, returnee Heikki Kovalainen and potentially homeless Nico Hulkenberg rounded out the top ten.

Felipe Massa, sporting a revised helmet livery to commemorate his last race with Ferrari, narrowly missed out on tenth spot, splitting the Saubers in eleventh, while Romain Grosjean - who complained of being baulked by Giedo van der Garde - was only 13th in the other Lotus. The Frenchman's 28-lap workload was beaten only by team-mate Kovalainen's 31, so his position wasn't due to a lack of running.

Force India made a low key to a weekend that team owner Vijay Mallya still views as important to the season as a whole, with Adrian Sutil 15th and James Calado 18th, sandwiching the two Williams drivers. At the back, meanwhile, van der Garde again set the pace, this time from Caterham team-mate Charles Pic.

Pirelli's 2014 slicks did see the light of day, albeit briefly, leaving the tyre company hoping for better conditions in FP2 in order to collect valuable data for their development process.