Lewis Hamilton has said that he was surprised by how qualifying unfolded at the Autodromo Hermanos Rodriguez, as Mercedes locked out the front row against the run of play.
Red Bull had dominated the weekend up until qualifying, but fell shy in Q3 as Mercedes came to the fore. Valtteri Bottas set the fastest time, with Hamilton slotting in behind in second place and just over a tenth down on the Finn.
Having finishing a quarter of a second clear of the two Red Bulls, Hamilton said the result came as shock to him.
"I've really no idea," Hamilton admitted after the session, when asked about what happened to give Mercedes the edge over Red Bull.
"They were like six-tenths ahead at some stage, then four-tenths, but whatever happened, we went into qualifying and we had better pace. I'm just as shocked as everyone, but we'll still take it."
Hamilton took the opportunity to praise Bottas for taking pole position, saying his teammate had simply done the better job.
"Valtteri did an amazing job. I'm so proud of Valtteri," Hamilton said.
"I mean, naturally, I'd love to be in his position. But, again, he did a fantastic Q3 run one. I gave it my all, but he did a better job today.
"I think he's been driving so well in these last few races. So it's really great for the team, they've been working so hard. We didn't think we had the pace this weekend, so to lock out the front row is pretty special.
"We'll have a good fight with the others tomorrow."
Video: The secrets of the Autodromo Hermanos Rodriguez circuit
Follow Rudy van Buren as he takes you on a flying lap around the Autodromo Hermanos Rodriguez, home of the F1 Mexican Grand Prix.