Mitch Evans ended the first free practice session in Sao Paulo fastest, as Jaguar set the pace in Brazil as the British team ended the session first and second.
Evans set a 1:12.555 on his final run of the session, but Cassidy finished two-tenths behind his teammate setting a 1:12.776.
Jaguar were five-tenths clear of the field in FP1, with Edoardo Mortara finishing in third place with a lap time of 1:13.096.
In the closing stages of the session, the track started to ramp up as the dust and dirt was cleaned off the racing line allowing for faster lap times.
Dan Ticktum finished first practice in fourth after setting a 1:13.138 for ERT. Pascal Wehrlein was fifth fastest after the German set a 1:13:179.
Maximilian Gunther was sixth fastest for Maserati. The 26-year old set a 1:13.214. Jake Hughes was seventh fastest for McLaren as the Brit 1:13.249.
Antonio Felix Da Costa was eighth quickest for Porsche. The season six champion posted a 1:13.259
Jehan Daruvala continued his fine form from Diriyah as he finished in ninth. The Indian driver was seven-tenths off Evans’ lap time.
Norman Nato was the tenth fastest for Andretti. The Frenchmen set a 1:13.354 to round out the top ten.
Sergio Sette Camara was 11th quickest in the first practice session. The ERT driver finished ahead of Sebastien Buemi in the lead Jaguar-powered Envision car. Buemi, and the Envision team, will be buoyed by the pace of the Jaguar in the opening session.
Reigning Champion Jake Dennis was 13th quickest, the Andretti driver finished ahead of Nico Muller and Jean-Eric Vergne.
Robin Frijns was 16th, the Dutchmen finished ahead of Lucas Di Grassi and Oliver Rowland.
Nyck De Vries was 19th. The season champion finished ahead of Sam Bird, Stoffel Vandoorne, and Sacha Fenestraz who rounded out the field.
