Reigning European F3 teams' champions Prema Powerteam dominated the pre-round F3 testing at Algarve as all four sessions were topped by the Italian team’s drivers.
It was Ferrari junior Lance Stroll who set the pace in the morning session of day one, ending up only 0.014s ahead of Motopark's Markus Pommer.
The 16-year-old Canadian stayed ahead after the lunch break as well, despite a small change in the layout that saw an extra chicane added to Turn 1 to prevent track limit abuse.
Fellow Prema drivers Felix Rosenqvist and Jake Dennis were second and fourth respectively in the first run on the modified circuit, while Pommer continued to show strong form in third.
While Stroll spent day two running largely outside of the top ten, Rosenqvist and Prema’s new recruit Nick Cassidy locked out both sessions of the day.
First, it was Rosenqvist heading the field in the morning with a 1m41.759s, followed by Cassidy and Carlin's George Russell.
But although that morning benchmark would remain unmatched, Cassidy, brought in for two rounds as Brandon Maisano's replacement, would end the testing on a high note as he beat Rosenqvist to the top spot in the afternoon.
Championship leader Antonio Giovinazzi, who returns to the series after his DTM debut last weekend, ended all four sessions in the top ten but with a best result of only fifth.
Fellow title contender Charles Leclerc managed to take a promising sixth in the first day’s afternoon session but failed to do better than 11th in the other three.
Alexander Sims, spearheading Hitech's return to Formula 3, ended day two in eighth place.