Carlos Sainz has continued the strong Ferrari showing in F1 pre-season testing in Bahrain by topping proceedings on Friday morning.
Already sitting second best late on, Sargeant improved inside the final 30 minutes of running to log a 1:32.666s.
On a set of the C5 tyres, he then went quicker still to record a 1:32.549s, just 0.063s off Sainz's best.
The Amrican's effort followed the team paying close attention to the front left corner of his car, though it was clearly not a lingering issue as he clocked more than 70 laps.
Fernando Alonso was also among the quicker runners with the Aston Martin driver third best.
The two-time F1 champion ended Thursday's running nip and tuck with Max Verstappen, who topped both sessions on the opening day.
The Dutchman was an observer in the morning with Sergio Perez getting his first taste of the Red Bull RB19.
Perez was prolific on track, building on the 157 laps set by his team-mate a day earlier by chalking up 76 laps.
Mirroring that reliability was Yuki Tsunoda for Scuderia AlphaTauri, who was the busiest driver on track with 85 laps, the most of anyone in the session.
Zhou Guanyu was fourth best though the Alfa Romeo looked stiffer than many of its rivals.
The Chinese driver had logged the fewest laps of all of those on track while only marginally better in terms of lap count was Esteban Ocon for Alpine.
While the lap times were unspectacular, there was more strong running from Mercedes as Lewis Hamilton managed 72 laps.
The Brit was only eighth best, ahead of McLaren's Lando Norris who logged an important 65 laps for the squad.
McLaren ended Thursday with the least recorded mileage of the test, the only team not to manage 500km of accrued running.
The latter stages of the session saw a systems check for the FIA, with a Virtual Safety Car and then the red flag being shown.
Running resumed once the cars had returned to the pit lane, with just over seven minutes left on the clock.
Testing continues in Bahrain this afternoon with most teams switching drivers; Sargeant, Alonso, and Zhou are the only three set to carry on.
Results: F1 pre-season testing, Day 2 (morning)
|Alfa Romeo Sauber