Mercedes' pre-season struggles led the team to hold an emergency meeting late on Friday, according to reports.
Mercedes' early struggles with car balance were compounded by lost track time after Hamilton picked up bodywork damage and Russell suffered a hydraulic failure.
Lewis Hamilton was pictured alongside Toto Wolff, chief mechanics and George Russell having what's believed to have been an emergency meeting late in the Sakhir evening.
The Silver – or, rather, Black – Arrows were cautiously optimistic that 2023 would be a bounce-back year but Friday's struggles have given cause for concern, especially after a hydraulic issue on George Russell’s car highlighted reliability concerns.
Hamilton ended Friday’s running in 13th place, two positions behind Russell who only managed 26 laps, as Mercedes continued to struggle with teething problems in the hotter sessions following a decent showing on a slightly cooler Thursday.
Andrew Shovlin, Mercedes’ trackside engineering director, said: "We've not had a strong second day – stopping on track with a reliability issue wasn't great and we have struggled to get the car balanced well across the changing conditions.
"We've got some investigations going on to understand why this has been such a challenge today when yesterday it was fairly straightforward. That work will continue into the night and no doubt we'll understand more come the morning."
Wolff: Problems are not drivers fault
Early on Friday, Wolff said that the drivers were unhappy with how the W14 was behaving.
"The car is out of balance this morning and you can see in the driving, leaving [tyre] marks on acceleration," said the Mercedes team principal. "It's hot and we just didn't find the right set-up for these conditions, which is part of the learning, I guess, with a new car.
"It definitely is not the driver who's overdriving the tyres or pushing it, it's the car that doesn't give him enough grip from the rear. So this is something we need to sort out over the course of the journey."