Drivers started the session on the intermediates after overnight rain in Mexico City left the circuit damp.
Conditions were tricky due to the combination of a wet track and the dust, with Sebastian Vettel reporting to his crew that it was "ridiculously slippery".
Max Verstappen turned the fastest lap for Toro Rosso at 1m25.990s, but what was even more surprising was the Mercedes duo down in 6th and 11th.
Both Mercedes' were having braking cooling issues and Rosberg's rear brakes actually caught on fire causing him to lose valuable time. With the thin air of Mexico City (2,200 foot altitude) the downforce from the wings is not as effective so stopping distances are elongated and the brakes have to work harder. Could this issue catch them out this weekend?
Daniil Kvyat, Kimi Raikkonen and Sebastian Vettel rounded out the top-5. Simulations have the lap times getting down to under 1m20s for qualifying.
|1||Max Verstappen||Toro Rosso/Renault||1m25.990s||0.000s||38|
|2||Daniil Kvyat||Red Bull/Renault||1m26.295s||0.305s||27|
|5||Daniel Ricciardo||Red Bull/Renault||1m27.185s||1.195s||28|
|8||Carlos Sainz||Toro Rosso/Renault||1m27.410s||1.420s||37|
|9||Sergio Perez||Force India/Mercedes||1m27.581s||1.591s||19|
|16||Nico Hulkenberg||Force India/Mercedes||1m29.099s||3.109s||16|