Max Verstappen pipped new Aston Martin signing Fernando Alonso to lead the times as Red Bull's new RB19 finally broke cover.
Most teams enjoyed a reliable start to the three-day test, as the porpoising problem that overshadowed the early running last year was largely put to bed.
PLUS: What we learned on day one of F1 testing in Bahrain
To reflect on the opening day's events, Alex Kalinauckas joins Martyn Lee straight from the Bahrain media centre to discuss Red Bull's strength, Ferrari's interesting first day, Mercedes' cause for optimism and much more.