Welcome to our LIVE commentary from this final practice session ahead of qualifying for the Brazilian Grand Prix at Interlagos.

The McLaren duo and the two Red Bulls get out on the track.

Hulkenberg lowers the bset lap to 1:20.5, looking a decent semi-wet pace.

Massa is taking it easy on this first lap with a 1:22.4, but is going round again - and his team-mate Fernando Alonso has just emerged from the pits in a set of intermediate tyres.

...aand it's a 1:21.277, just as Ferrari's Felipe Massa gets out on the track.

Hulkenberg is having another crack and flying...

Williams driver Nico Hulkenberg has just posted a 1:21.976 - but the rain starts falling once more. So much for the weather clearing up!

Barrichello comes round again and posts a 1:22.6, the best lap so far - but the flying laps are starting to come thick and fast.

Ferrari have their tyre warmers on - looks like Alonso will be out shortly...

Brazilian legend Rubens Barrichello is now out on the track, and is just under a second and a half behind Heidfeld's pace with his first full lap.

Glock has posted a second flying lap and clipped a second off his time, but Nick Heidfeld has just put in a 1:23.897.

The weather forecast for tomorrow is outstandingly good, so qualifying later on will be crucial.

Tyre strategy is critical today: with only four sets of intermediate tyres for each car the teams will want to hang on to them all in case of rain in the race itself.

Glock comes in with a 1:25.972 - that's 14 seconds slower than the best of yesterday's laps!

Timo Glock is out on the circuit and looks to be trying to post a time - he's the quickest man out there so far.

While you're waiting for the action to start why not read the undisputed funniest story of the week from Brazil:

The two McLarens are still being prepared - with the word being that both will gamble on running a wet race set-up in qualifying to try and get onto the grid.

Still no completed laps to report.

The McLaren drivers will be delighted to see some rain - both Lewis Hamilton and Jenson Button admitted that they were off the pace yesterday, but in the rain both would like their chances of trying to sneak a result on Sunday.

Latest weather forecast suggests that it will continue to get drier for at least the next half hour.

Here comes Sebastian Vettel, who has to be favourite for the race after he topped practice yesterday... so long as he finishes, of course.

HRT's Bruno Senna comes out to huge roars from his home crowd on a day of big news for his team.