Mercedes looked a long way off the pace in practice for the Bahrain season-opener on Friday and seven times Formula One world champion Lewis Hamilton and new team mate George Russell saw no quick fix.
Hamilton was ninth in the second session at Sakhir, with Russell fourth. The pair were seventh and fourth respectively in the opening practice.
Red Bull's world champion Max Verstappen topped the timesheets with Ferrari's Charles Leclerc and Carlos Sainz second and third in practice two.
"It's all about lap time and we're certainly not where we want to be," said Russell.