Lando Norris felt his quickest effort during practice for the Mexico City Grand Prix was "too quick" for so early in the weekend as he nipped at Max Verstappen's heels.
Fresh off securing a podium for the fourth straight race last time out in the United States, Norris finished second quickest at the Autodromo Hermanos Rodriguez with a time just 0.119s slower than Verstappen's benchmark of a 1:18.686 on the Soft compound Pirellis.
Norris clocked up 30 laps for the team at a track he warned would not suit the MCL60 package, with a number of slow-speed corners - but the Briton still managed to pull out a strong time on the low fuel runs, surprisingly something he regretted.
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Norris: Things could switch very quickly either way
"Many drivers were within three-tenths, but I think it was a good Friday and good start to the weekend," Norris told F1 TV with the top eight drivers down to Esteban Ocon close behind Verstappen.
"Things could swing very quickly either way. I did a very good lap, maybe it was too good for this early in the weekend, but we'll continue to try and improve.
"We generally always start weekends off quite well, and we always have a good idea of where to put the car to begin with, and it's not far normally where we end up.
"There's always little things that add up and stuff to improve from my driving, little things here and there, but to challenge the Red Bull [for pole and the win], I think is going to be tough around here."