Daniel Abt topped the times after a flurry of late fast laps in the first free practice session ahead of the Mexico E-Prix.
Abt jumped to the top of the times in the closing minutes of the opening session in Mexico, finishing the morning less than a tenth of a second quicker than Venturi's Edoardo Mortara in second.
Mortara had only topped the times a few moments before Abt crossed the line, knocking his Audi Sport Abt Schaeffler team-mate Lucas Di Grassi off the top spot.
Di Grassi fell further down the order as multiple drivers found improvements in the closing stages of FP1. Alexander Sims finished the morning third, ahead of Sebastien Buemi, Oliver Turvey, and Di Grassi.
Stoffel Vandoorne was briefly top of the order in the middle of the session, but dropped down to seventh.
Antonio Felix Da Costa, championship leader Sam Bird, and Jose Maria Lopez rounded out the top 10.
Multiple drivers made use of the limited run off areas as they locked up and pushed the limits, including Lopez, Robin Frijns and Mitch Evans, but the only driver to make contact with any walls was Gary Paffett. In the final five minutes of the session, Paffett suffered a snap of oversteer and tapped the rear of his Venturi, damaging the rear suspension and ending his session early.
Championship newcomer Felipe Nasr finished P12, behind Santiago podium finisher Pascal Wehrlein.