Mercedes team principal Toto Wolff has described qualifying for the Abu Dhabi Grand Prix as a "toilet day" after Lewis Hamilton and George Russell ended the session fifth and sixth.
The Silver Arrows took a first victory of the season through Russell in Brazil last weekend and topped the opening practice of the weekend on Friday at Yas Marina.
But by the end of the hour of qualifying, Hamilton was two-tenths adrift of fourth-placed Carlos Sainz and 0.684secs down on polesitter Max Verstappen.
"Today I heard is world toilet day, it is one to put in the toilet," Wolff told Sky Sports F1.
"We didn't get the job done, we went backwards and they [Red Bull and Ferrari] did a step forward.
"We tried the high-downforce, high-drag concept to give us a good race car tomorrow and that was just so slow on the straights that it didn't give anything."
Russell was seen testing a lower-drag rear wing through practice compared to Hamilton, who was running the higher-downforce component fitted to both W13s before the parc fermé cut-off.
Asked why the drivers were not split in terms of set-up, Wolff explained: "We have the belief that for tomorrow, it is so much better, it has more downforce to protect the tyres.