Ahead of today's second free practice session the air temperature is 24 degrees C, whilst the track temperature is 34 degrees. It is bright and the sun is out.

Lewis Hamilton topped the timesheets earlier, surprisingly, 0.808s ahead of his Mercedes teammate Nico Rosberg. Indeed, Rosberg wasn't second quickest, the Silver Arrows pairing split by McLaren's Jenson Button.

While Ferrari is expecting a difficult weekend, Fernando Alonso was fourth quickest and Kimi Raikkonen seventh, with Sergio Perez also impressing despite missing most of the session.

As ever, drivers are struggling for grip and consequently we've seen a number of 'excursions', mainly at the chicanes.

Courtesy of sheer grunt, as opposed to aero, the Mercedes-powered teams are expected to excel here whilst Red Bull, so strong at Spa, where it mattered, will struggle. With an eye on the high speeds achieved here, brakes will also be a concern, certainly for some teams.

Both Red Bull drivers had DRS issues early this morning, while Ricciardo missed the last twenty minutes of running with an "ERS-related issue".

Tyres this weekend are hard and medium, with the options making their appearance in the next ninety minutes.

The lights go green, however it is a couple of minutes before a driver (Grosjean) heads down the pitlane to get things underway. He is joined by Bianchi, Ericsson and Chilton.

Grosjean gets it all wrong at the second chicane and resorts to suing the generous run-off. He finally stops the clock at 1:32.995.

Ricciardo, making up for lost time this morning, posts 29.376 but this is soon beaten by Kvyat who crosses the line at 28.552.

Having gone third (28.578), Hulkenberg immediately goes quickest in S1 of his next lap as teammate Perez goes quickest overall (28.270).

For the third successive lap (seriously), Grosjean makes a hash of the second chicane. Ricciardo making full use of the artificial grass in the Parabolica.

Magnussen goes quickest in all three sectors, the Dane posting 27.634. McLaren looking strong here today.

As Rosberg looks to improve on 35.088, there are problems with his teammate's car which is up on its stand after failing to start three times. Back on track Rosberg posts 27.500 to go quickest. The German subsequently complains of a vibration from his right-front... just as the mechanic remove the floor from Hamilton's car.

Alonso goes third (27.101) and Raikkonen fourth (27.392), the Finn sliding beautifully in the entry to the Parabolica.

No sooner has Button gone quickest with a 26.975 than Alonso breaks the timing beam at 26.790. Much to the delight of the tifosi.

A 26.786 sees Rosberg re-take the top spot, as Vettel goes fifth (27.150), ahead of Bottas and Massa.

Told that he forgot to press the overtake button, Vettel laughs and admits he forgot. "I'll do it next time," he promises.

Despite being side-lined in what is a crucial session, Hamilton looks quite relaxed at the back of the garage as he chats with team guests. Team bosses Toto Wolff and Niki Lauda look equally relaxed as they chat elsewhere.

Hulkenberg complains that drivability out of T2 is not good. "There is some hesitation," he says.

Just over thirty minutes into the session Magnussen is the first driver to make the switch to the option rubber. His first lap however is slower than on the primes.

Though he now goes quickest in S2, Magnussen remains fourth (27.014). The Dane is subsequently advised that he had run out of electrical charge hence the failure to improve.

No such problems for Rosberg, who is also on options now, the German posting 26.225. Bottas (option) posts 26.758 to go second.

As more drivers switch to the softer rubber Vettel goes fourth (26.844).

Sutil runs over the kerbs at the second chicane, Rosberg misses the first and Magnussen runs wide at Ascari.

Button goes third (26.762) and Alonso fourth (26.790), as Rosberg looks to improve again. Still no sign of Hamilton coming out.