Lewis Hamilton fears the tyre degradation Mercedes encountered in Friday's practice could imply a "three of four stop kind of thing" for Sunday's Mexican Grand Prix.
Hamilton topped the morning session but was well off the pace in FP2 which he concluded P5, just behind Mercedes teammate Valtteri Bottas but almost a full second adrift from pace-setter Sebastian Vettel.
While the Briton's speed on the medium tyre during race simulations appeared adequate, his single-lap pace on the soft compound was sub-par and quickly undermined by degradation and graining.
Hamilton suggested that Mexico City's rarefied air which is forcing teams to run high downforce set-ups is having a detrimental impact on handling and subsequently on tyres.
"It's pretty useless here with the tyres, it feels like we're going to be doing a three or four stop kind of thing," Hamilton said. "This place is so aggressive on the tyres.
"As the tyres are starting to grain, it gets a lot easier to lock the tyres up. One lock up on these things and they're like 50p coins. It's rattling your teeth out.
"Fortunately today I didn't have any of that, I'll try to avoid that.
"We have massive downforce but low air density so you're just sliding around a lot. It'll be interesting. We've got another DRS zone, so I hope that helps us get closer for the racing."
Hamilton admitted that a fair amount of set-up work was still required on his W10, as well as some personal improvement.
"The track shifted a little bit in terms of its grip level and temperature, and we didn't really get the set-up quite perfect," he said.
"Even within myself, I didn't quite get the lap perfectly together. So I'll be studying that myself tonight to try and figure that out."
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