Max Verstappen wrote a small slice of Formula 1 history as the sport returned to Mexico, but his fastest time in opening practice included him straightlining the revamped Esses.
Toro Rosso's Verstappen was three tenths faster than the Red Bull of Daniil Kvyat, but clearly cut the left-hand element of the exit of the Esses sequence to do so.
Newly-crowned world champion Lewis Hamilton was only 11th fastest.
Story of the session
It was the first competitive F1 running at the Autodromo Hermanos Rodriguez since 1992, with Lotus's Pastor Maldonado the first driver out around the revamped 2.67-mile circuit.
The track was very slippery from the start, with damp patches from morning rain not helping the grip from the new asphalt. All cars used intermediate tyres for their first runs.
"It's so slippery everywhere, it's like there's oil," complained Verstappen, as plenty of cars went on to the run-off at Turn 10. "Quite a strange feeling," reported McLaren's Fernando Alonso.
Raikkonen posted the first laptime, 1m37.169s, before Verstappen's 1m35.283s that included an off-track excursion. As the track dried under weak morning sunshine, Daniil Kvyat took P1 with 1m34.041s before Carlos Sainz set 1m33.095s, all on intermediate rubber.
"Too dry for inters, but super slippery everywhere," said Vettel.
Slick tyre running
Valtteri Bottas was the first driver to set a time using medium-compound slicks, taking P1 with 1m32.389s. He improved to 1m30.678s, as Hamilton went P2, half a second off after straightlining the Esses.
Ricciardo took the top spot at the halfway mark of the session, as Red Bull chose to run on a clear track, with 1m30.577s then a 1m29.502s. Alonso went P2 on 1m30.125s, with Lotus's 2016 signing Jolyon Palmer briefly grabbing the top spot at 1m29.163s.
As the times tumbled, Rosberg set 1m28.399s with Hamilton P2 on 1m28.444s.
Felipe Nasr was the first spinner of the session, looping around under power as he rejoined the old Peraltada section of the circuit.
Rosberg improved to 1m27.226s, and was going quicker still when he went off track with a brake problem entering the Stadium section, rejoining with his left-rear corner well ablaze. The conflagration blew itself out as he returned to the pits.
Hamilton was also warned: "You're going to have to cool these brakes down, they're too hot."
Kvyat moved to the top of the times, first setting 1m26.663s and then 1m26.295s, with Riccardo in P2 on 1m27.185s, eight tenths down. Raikkonen improved to P2 on 1m26.877s, and Verstappen rose to third on 1m26.918s.
Verstappen went even faster, a 1m26.602s pipping Raikkonen for second, and a 1m26.495s just two tenths off Kvyat.
He then eclipsed the Russian with 1m25.990s despite blatantly cutting the final element of the Esses. His time wasn't deleted, however, which will lead to questions over track limits at this section of the circuit.
Vettel went fourth quickest with six minutes remaining, as Raikkonen improved his time to 1m26.295s but not his position.
Behind Ricciardo and Rosberg, Valtteri Bottas was seventh for Williams ahead of the second Toro Rosso of Carlos Sainz and Force India's Sergio Perez and Williams's Felipe Massa.
Other incidents of note
Alonso suffered a cut on his set of medium tyres, and was forced into inters again for his second run.
Verstappen spun at Turn 1 and rejoined, and Bottas spun at Turn 3 while practicing his racing lines against Hamilton.
Near the end of the session, Perez locked up and was forced to spin turn back on to the track.
|1||Max Verstappen||Toro Rosso||1:25.990||38|
|2||Daniil Kvyat||Red Bull Racing||1:26.295||+0.305||27|
|5||Daniel Ricciardo||Red Bull Racing||1:27.185||+1.195||28|
|8||Carlos Sainz Jr.||Toro Rosso||1:27.410||+1.420||37|
|9||Sergio Perez||Force India||1:27.581||+1.591||19|
|13||Pastor Maldonado||Team Lotus||1:28.559||+2.569||30|
|15||Jolyon Palmer||Team Lotus||1:28.711||+2.721||24|
|16||Nico Hulkenberg||Force India||1:29.099||+3.109||16|
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