Ahead of today's free practice session the air temperature is 20 degrees c, while the track temperature is also 20 degrees, slightly warmer than yesterday's opening session.

The fog that limited track-time yesterday has not returned, there is however a much stronger wind hitting the Circuit of the Americas.

Having had an unusually anonymous opening session yesterday, Sebastian Vettel was the pace-setter in FP2, the world champion heading a Red Bull 1-2. Indeed, the Austrian outfit looks very strong here, as it has looked at every race since the summer break.

The Mercedes were up there, and while Lewis Hamilton insists his recent form has been shocking the German team should further consolidate its runner-up spot in th Constructors' Championship.

The big surprise was the 'out of the box' pace of Heikki Kovalainen who is replacing Kimi Raikkonen at Lotus for the final two races. The Finn out-paced Romain Grosjean in FP2 and while we expect the Frenchman to be very much in the mix today and tomorrow, a strong performance from Kovalainen could yet see Ferrari lose out on third place in the championship.

One has to feel for Fernando Alonso and Sergio Perez. With the Ferrari still struggling for grip, the Spaniard has to contend with the back problem he suffered in Abu Dhabi and also an injured thumb. Meanwhile, the Mexican is steel clearly reeling after being dumped (for 2014) in favour of Kevin Magnussen.

Both Saubers were strong yesterday while Jenson Button picked up a three-place grid penalty for overtaking whilst the session was being red flagged.

The tyres available this weekend are hard and medium, while there are two DRS zones, one on the pit straight while the other, as in 2012, runs between Turns 11 and 12.

We could well be looking at a one-stop race for most runners, as was the case last year, although some may try two stops if they feel it offers a speed advantage. Wear and degradation is where we would expect it to be: the medium will be the one to qualify on, while we're seeing very little degradation on the prime tyre - which is just under a second slower than the medium tyre.

It was a dreadful day for Marussia yesterday, regular drivers Jules Bianchi and Max Chilton, and reserve driver Rodolfo Gonzalez, all encountering problems, the Frenchman with balance and the Englishman with brakes. As the Anglo-Russian outfit battles with Caterham for tenth in the standings - and that all-important prize money - it will be hoping for a better day today.

A number of corners were catching drivers out yesterday, particularly Turns 1 and 19.

As in both of yesterday's sessions, 'new boy' Kovalainen is first out. He is followed by Gutierrez, Grosjean and Hulkenberg.

Bianchi is the first driver to post a time, the Frenchman stopping the clock at 1:44.983. Moments later however, Ricciardo crosses the line at 42.450. On their subsequent laps Bianchi posts 43.690 and Ricciardo 40.098.

As Rosberg is told not to go slow as the team want his tyres warmed up as soon as possible, Hamilton complains that he is unhappy with his practice start. "The car doesn't hardly move when I engage the clutch," he moans.

As Ricciardo posts 39.130, di Resta goes second ahead of Rosberg, Vergne and Van der Garde however, moments later a 39.583 sees Hamilton go second.

Grosjean is told that both Mercedes are thought to be on high fuel.

Sutil goes quickest with a 38.559 as Vergne posts 39.036 to take third.

Pic, who has already incurred a five-place grid penalty after his team opted to change his gearbox, is having the rear anti-roll bar changed.

Grosjean (38.307) and Rosberg (38.625) split the force Indias at the top of the timesheet as Sutil consolidates his top spot with a 38.289.

A 38.158 sees Webber go straight to the head of the queue, the Australian much happier with the prime tyre here yesterday. As Hamilton goes fourth (38.462)m Kovalainen goes fifth.

Sutil runs wide in T19, a corner that caught him out numerous times yesterday. Moments later, Grosjean improves with a 37.829 to go quickest.