RACE DEBRIEF

    Hot and humid conditions greeted the F1 fraternity at the Circuit of The Americas on Friday, as practice for the United States Grand Prix got under way. Here are five things we learned from the first day's running…

    1. Mercedes hold the edge but engine reliability concerning

    The Circuit of The Americas is Mercedes territory, the Silver Arrows having taken pole position in every race since the hybrid turbo era began. And that advantage looked locked in again after first Friday practice as they ended up nearly a second clear of Red Bull.

    But as temperatures rose for second practice, Mercedes seemed to slip back, both drivers struggling for grip with the rears prone to overheating. That said, Lewis Hamilton would have been quickest if he put all his best mini sectors together, according to our data, rather than Sergio Perez, in FP2.

    And our qualifying simulation data has Mercedes holding an impressive 0.33s advantage over championship rivals Red Bull – one of their most significant gaps all year.

    It’s less promising in terms of race pace, with Red Bull the quicker on long runs, with a 0.13s advantage. But that is perhaps not a surprise given Hamilton and Valtteri Bottas were unhappy with the balance and felt the car wasn’t easy to drive in the afternoon.

    Plenty of work to do overnight, then, to find the perfect set-up – but they’ve shown time and time again that they’re able to find time ahead of qualifying. More challenging, though, is their engine reliability, which has been unusually unpredictable of late.

    Mercedes boss Toto Wolff admitted to me that reliability is a concern after they were forced to change Bottas’ engine for the second time in three races, moving the Finn onto his sixth internal combustion engine – more than double his permitted allocation.

    Qualifying Pace Lap.jpg

    2. Red Bull offer real threat to Mercedes dominance

    Red Bull turned things around in a matter of hours on Friday, the four-time world champions looking like they were nowhere in opening practice – but they were far more competitive when things warmed up in FP2, even if Max Verstappen was frustrated not to get a clear enough lap to set a low fuel timed run.

    Perez was particularly impressive, the Mexican looking comfortable with the RB16B from his first turn of the wheel in Austin. He reckons if they can find a couple of tenths overnight, he should be in the mix for pole.

    READ MORE: Perez leads Norris in second practice as frustrated Verstappen falls foul of traffic

    Intriguingly, he also thinks there’s “some margin to improve our long run pace and tyre degradation” that would extend their already strong form with fuel. Add in their performance edge over Mercedes in the medium and high-speed corners and this puts them in very good shape for Sunday afternoon.

    Race Pace Lap.jpg

    3. Ferrari and McLaren fight too close to call

    McLaren expected Austin to suit them more than Turkey, and the early signs are that will be the case this weekend. Lando Norris and Daniel Ricciardo were both inside the top five, with P3 rivals Ferrari seventh and ninth.

    However, they are much closer when you look at the ideal lap data (below), with Norris and Ricciardo sandwiching Charles Leclerc and Carlos Sainz, the latter leaving the most lap time on the table of anyone – at around 0.73s.

    READ MORE: Norris says late set-up changes key as he takes impressive P2 in Friday practice at COTA

    Our short run data suggests McLaren have around three tenths of a second advantage over Ferrari, with Aston Martin splitting them. But it flips around when looking at race pace, with Ferrari heading McLaren by the same margin (see the two graphs above).

    All have said there is plenty more to come if they can get the balance to their liking, but as it stands, the duo are in for another tight fight.

    Ideal Lap FP2.jpg

    4. Mixed fortunes for Aston Martin and Alpine

    Lance Stroll looked in fine form on Friday, but his Aston Martin team mate Sebastian Vettel struggled a little more – and faces an uphill battle this weekend after a suite of engine component changes means he’ll start from the back of the grid.

    Their qualifying pace looks strong enough to get both cars into Q3 – though Vettel is unlikely to run more than one segment of qualifying because of his penalty. But their race pace is a little less impressive, with the green cars closely matched with Alpine and McLaren.

    READ MORE: Bottas, Russell and Vettel hit with United States Grand Prix grid penalties after PU changes

    Alpine had a mixed day, too. Fernando Alonso had an uncharacteristic spin at the end of FP2 as he struggled to get comfortable with the car and lost a significant amount of time after an operational issue forced him to stop out on track in FP1.

    But Esteban Ocon, who was running the visor cam, was much more consistent and told me he felt they can be contenders for points once more in Austin. They may well have to work for it, though, with Alpine sixth-best in qualifying sims – but if they can overtake, their race pace puts them in the top four, two tenths shy of Ferrari.

    Car Performance FP2.jpg

    5. Warm weather set to spice up the race weekend

    It has been uncharacteristically hot in Austin so far, with temperatures in the high 20Cs and humidity high. That made life tricky for the drivers, with the rears on the softs suffering from a bit of overheating.

    Pirelli boss Mario Isola said the rears are “quite stressed given the severe traction demands of this circuit in the final sector especially”.

    He added: “Managing the soft tyre looks to be key, and this is something that the teams will be looking at in more detail tomorrow, with some likely to try and get through Q2 on the medium tyre in order to start with it on Sunday and open up a wider range of strategic possibilities for the race.

    “However, with a bigger performance gap compared to the soft than we saw [in FP1], the soft certainly has its advantages too: especially with a two-stopper looking likely."

    Tyres will be a talking point all weekend. The potential for multiple strategies and likelihood of two-stops minimum is an exciting prospect and sets the scene for an exciting Grand Prix that will take place in front of a sell-out 140,000-strong crowd.

    HIGHLIGHTS: Watch the key moments from second practice for the United States GP at COTA