Hello and welcome to coverage of FP3 from the Italian Grand Prix at Monza.

So Hamilton quickest again - but only by a whisker from Alonso. Will it be those two on the front row in qualifying. Join us at 13:00 UK time to find out!

The top 10: Hamilton, Alonso, Di Resta, Massa, Button, Rosberg, Perez, Raikkonen, Hulkenberg, Maldonado.

Perez a late improver - up to 7th at the death.

SESSION OVER! Drivers finishing their laps - but it's a slightly muted end to the session after Vettel's woes.

Yellow flags out as engineers deal with Vettel's car - replays show that he had a loss of power and chose to back off - he told his pits it was a 'low battery'.

VETTEL HAS STOPPED! Not sure what's happened there, but the car is parked up by Ascari.

Button has another go at setting a new best, but finds traffic in the form of Raikkonen at the end of the lap.

Vettel a late arrival into the action. Team-mate Webber down in 12th, almost a second back, the Red Bulls looking a slight concern in qualifying.

And Hamilton does lead! By the slenderest margin possible in Formula One - 0.001 seconds. 1:24.578 is the new benchmark.

Alonso has shaved six-hundredths of a second off his leading time - so it will be just that fraction more difficult for someone to eclipse him. Hamilton doing his best to do so...

Replays show Raikkonen having a bit of a wobble in the Parabolica - just as Massa had done a minute or two earlier. Neither better their earlier times.

Button round again in a 1:25.0 - so no gain there. Jenson was complaining of understeer earlier, although frankly it wouldn't be a practice session if the McLaren man wasn't doing that.

Alonso finds himself on the back of Rosberg - but the tow actually plays into his favour, helping him set a fastest sector time in the final sector. No overall improvement, however.

Small improvement for Button - a 1:24.994 that cements his third place. Those tyres may still warm up a touch with another lap or two, just like the hard compound tyres have done.

Button, sure enough, is followed out by Hamilton, the Ferraris, and Raikkonen. Rosberg, the only other man in the top six, was already running.

Predicted gains are supposedly 0.3-0.5 seconds on the medium compound compared to the hard, the F1 pit crews are predicting. We'll see.

Button out on track - medium rubber - he's the first, and he won't be the last.

A lot of focus on Monza, but since we're in Italy it would be remiss not to mention the achievement of former F1 star Alex Zanardi, who's won Paralympics gold this week.

A slightly quiet spell here - we've not seen the big names go out on the medium compound tyres yet. We could be in for a little flurry of activity towards the end of the session.

Hamilton given some tips about where Alonso gained his speed - he is told that Alonso was "one foot outside the white line" at Ascari, running just out on to the astroturf beyond the kerb.