Charles Leclerc ended the final morning session of pre-season testing from Bahrain on top of the timesheets.
The Monegasque driver bested George Russell in the Mercedes, who returned to the track after a hydraulic problem brought an early end to his session on Friday.
There were two red flags during the session, the first of which was called for debris on the circuit.
However, the second red flag was deployed after Alfa Romeo’s Valtteri Bottas stopped on the track with an issue.
It was also a difficult session for McLaren, who clocked just 44 laps through Oscar Piastri.
The Woking-based squad was forced to spend a lot of time in the garage to fix an issue with its front wing.
“The team are currently conducting some temporary strengthening work on the front winglets to ensure we can complete today’s running,” it clarified during the session.
“It’s a very minor issue that will be permanently fixed for the Grand Prix next weekend.”
Felipe Drugovich was called back up for Aston Martin for the morning and ended up in third place amid rumours that he will be called upon to race for the team next week in place of the injured Lance Stroll.
Sergio Perez was fourth fastest and will carry over driving duties for Red Bull into the evening.
Pierre Gasly was fifth for Alpine, ahead of Alexander Albon for Williams.
Nico Hulkenberg was seventh, while Oscar Piastri was eighth for the troubling outing for the McLaren team.
Bottas’ stoppage saw him finish the session in ninth place, while the top 10 was rounded out by AlphaTauri’s Nyck de Vries.