Russell, who has been a victim of porpoising over the three days, has acknowledged that the performance from the W13 simply has not been there.
Hamilton denied claims that Mercedes were sandbagging at the Sakhir track, despite them finishing behind Ferrari and Red Bull.
Mercedes' Hamilton and Red Bull's Verstappen will be renewing their rivalry at the 2022 F1 Championships.
Gasly set a time of 1:33.902, replacing Ferrari's Charles Leclerc at the top who went fastest in the first session.
F1 pre-season testing is a time of optimism and renewed hope for many, but the time-sheets don't always tell the full story.
Masi's future was a major topic of discussion throughout the off-season, following the contentious decision-making in Abu Dhabi.
The British Formula One-ace is confident of his team Mercedes' chances with new-regulations coming in to play in the 2022 F1 Championship.
The Mercedes F1 team might want to explore certain design options of Red Bull's 2022 Formula 1 car, the RB18.
George Russell, who will be part of the Mercedes F1 team alongside Lewis Hamilton this season, raised eyerbrows with his statements made earlier this month.
Michael Masi was removed from his post by the FIA after his controversial call which afforded Verstappen the chance to beat Hamilton.