Lewis Hamilton described the lack of grip at the Autodromo Hermanos Rodriguez as 'crazy' following Friday's practice sessions at the circuit.
Formula 1 has returned to Mexico after a 23-year break and Hamilton had a low-key day, placing fourth after a spin in the second session.
"It was really challenging out there today - for everyone I think - but also a lot of fun," he said.
"The track feels more like a go kart track in the slow areas! It's crazy how slippery it is.
"Because we're so high up in terms of altitude, there's even less grip than in Monza, so the car was just sliding around.
"Of course, this is also because the track is new, so there is no rubber on it yet. But it's getting better and better the more we drive."
Mercedes team-mate Nico Rosberg ended the day on top.
"I was happy with the outcome today," he said. "It seems that we are quick and I was able to try a lot of different things with the car. I'm really enjoying it here and I can't wait for qualifying and the race."