Sergio Perez has warned of an unpredictable qualifying for the Mexico City Grand Prix with the top six drivers seemingly all in contention for pole position.
There was little to separate Mercedes, Red Bull and Ferrari on Friday at the Autódromo Hermanos Rodríguez with just 0.142secs separating Carlos Sainz at the top of the timesheet and Lewis Hamilton in fifth in the opening session.
Whilst FP2 focused on Pirelli's prototype test, the five drivers who had given way to rookies in FP1 were allowed runs on this year's rubber for the first 45 minutes, with Mercedes' George Russell setting the fastest time of the day.
Perez, who is embroiled in a tight battle with Charles Leclerc for second in the drivers' standings with just two points separating the pair, described Friday's running as "a tricky day as usual in Mexico" given the altitude.
"Everything is floating around so it's fairly easy to make mistakes in these conditions," added Perez.
"Obviously, FP2 was mainly for Pirelli but in FP1 we got a good base and we seem to be there. Ferrari seems to be strong and also Mercedes, so it is going to be a tough battle [in qualifying]."
Looking ahead to that all-important qualifying hour, Perez added: "It should be straightforward hopefully, but you can always expect different things [to happen]."