Mitch Evans ended the opening test session in Valencia quickest setting a 1.24.474 for Jaguar.
The Kiwi posted his time on the last flying lap of the session to pip Antonio Felix Da Costa who set a 1.24.617 to end the session in second for Porsche.
Sebastien Buemi was third fastest in the Jaguar-powered Envision car setting a 1.24.671 after completing 41 laps during the session.
In a session that was filled with rookie drivers, as the teams had to place a rookie driver in at least one session across the three days, there was only one red flag which occurred on the two-hour mark, as Robert Schwartzman came to a halt in the Ds Penske in the final sector.
At the start of the three-hour morning test session, it was the McLaren of Jake Hughes who was leading the way in the early stages. He was soon displaced by Jean-Eric Vergne in the Ds Penske.
Then the McLaren of Taylor Barnard jumped to the top of the timesheets with a 1.24.929, the British driver who was stepping in for Sam Bird during the mornings running impressed throughout the session, eventually ending up in seventh place.
In the final hour of running, Da Costa jumped to the top of the timesheets and looked like he would end the morning session fastest until Evans managed to squeeze past him by a tenth of the second at the chequered flag.
Behind Buemi in third was Edoardo Mortara, who was having his first experience of driving the Mahindra car around Valencia. The Swiss-Italian driver set a 1.24.701 across his 40 laps.
Pascal Wehrelin was fifth fastest in the second Porsche. The German set a 1.24.764 and completed 43 tours of the circuit.
Maximilian Gunther, who was fastest in five of the six sessions last season, was sixth fastest and three-tenths behind the lap time set by Evans.
Bernard was the quickest rookie in seventh with Nico Muller behind him in eighth place in the lead ABT Cupra car.
Sergio Sette Camara was ninth in the newly rebranded ERT team, and Jaguar’s newest recruit Nick Cassidy rounded out the top ten.
Norman Nato, who was driving the Andretti for the first time was 11th, the French driver was eight-tenths off the lap time set by Evans.
Lucas Di Grassi was 12th on his return to ABT team, with Jehan Daruvala ending his first session for Maserati in 13th.
Jean-Eric Vergne was 14th for Ds Penske, Robin Frijns was 15th on his return to Envision Racing, and Dan Ticktum completed most of his running in the latter stages of the session was 16th.
Robert Schwartzman was 17th after he stopped on the track, and was unable to compete in the last 45 minutes of the session.
Jake Hughes ended the session 18th for McLaren, whilst Victor Martins was 19th for Nissan, and Luca Ghiotto in the second Nissan in 20th.
Zane Maloney was 21st fastest for Andretti as he deputised for World Champion Jake Dennis. Season 7 champion Nyck De Vries ended the session 22nd in his first taste of the GEN 3 car.