Lewis Hamilton led the way for Mercedes in an unrepresentative first practice session at the Mexican Grand Prix.
The Briton took advantage of a clearer track, immediately following a red flag caused by Lance Stroll, to post a 1m17.327s and lead Charles Leclerc and Max Verstappen by a tenth of a second.
It was a slow start on a cool, overcast morning at the Autodromo Hermanos Rodriguez as a damp track from overnight rain meant the initial installation laps were conducted on intermediate tyres.
By the time the first timed runs began, however, slicks could be used and lap times tumbled as a result.
The early pace was set by Charles Leclerc on a 1m18.8s for Ferrari on the medium compound tyre, but grip was still very much at a premium with a number of drivers locking up at Turn 1 and Turn 12 and sliding in the tricky middle sector.
Indeed, Max Verstappen, on the softs, may well have set the fastest time on the first set of tyres without running wide entering the stadium section.
Into the second part of the session and Alex Albon jumped fastest just before Stroll slid into the barrier at Turn 15, causing a lengthy suspension of running as the Tecpro was repositioned.
That left teams with just 20 minutes to complete their second series of runs and it was then Lewis Hamilton posted his quickest time on the fastest compound.
A big issue though was traffic in the final sequence of corners with Vettel and Verstappen involved in a fracas in the stadium, the Dutchman narrowly avoiding contact with Kevin Magnussen’s Haas.
The mess in the final sector also meant many drivers laps were compromised, with Max and Leclerc missing out on laps that could have challenged the Mercedes.
On a positive note for the Monegasque, his best time, good enough for second, came on the medium compound tyre as he also set the fastest top speed at 224mph on the approach to Turn 1.
Verstappen followed in third with Albon half a second down in fourth in the second Red Bull and Bottas unable to break into the 1m17’s in fifth.
For Vettel, in addition to traffic issues, two big lock-ups into Turn 1 left the German with flat-spotted tyres compromising his pace his sixth.
Carlos Sainz continued to keep a stranglehold on ‘best of the rest’ in seventh for McLaren, ahead of the two Toro Rosso’s in eighth and ninth.
Completing the top 10 was Antonio Giovinazzi in the Alfa Romeo, as he continues to lead teammate Kimi Raikkonen, with the Finn in 13th.
After the disappointment of their Japan DQ, Renault had a slow start to the weekend in Mexico, with Nico Hulkenberg 11th and Daniel Ricciardo 15th.
Racing Point will also look to make progress with Stroll 16th despite his off, just ahead of local hero Sergio Perez in 17th.
Romain Grosjean lost his best time in the session for exceeding track limits at Turn 11 and, as a result, fell to 18th.
While at Williams, George Russell was a second clear of potential 2020 teammate Nicholas Latifi as the Canadian made his first appearance since Spa.
A reason for the gap, however, is Latifi was running older parts on his car as the Grove-based squad complete aero evaluations.
Full results from Practice 1 in Mexico can be seen below:
