Mercedes team principal Toto Wolff has bemoaned the "total underperformance" of "everybody involved" after finishing qualifying for Formula 1's Hungarian Grand Prix fifth and 17th.
George Russell endured a self-confessed "disaster" after failing to advance from Q1, a mistake at Turn 8 on his most crucial effort - at the same time team-mate Lewis Hamilton had gone top of the timesheet - leaving him vulnerable.
With a rush of drivers trying to improve after a red flag stoppage following a crash for Red Bull's Sergio Perez, Russell failed to improve on an initially damp track before pitting as rivals made the most of track evolution to dump the Briton out of qualifying.
While Hamilton progressed, the rising track temperatures conspired to prevent a tilt at pole position and left the seven-time champion struggling even to make Q3 - only scraping through to the final part of qualifying by 0.010 seconds from Nico Hulkenberg's Haas.
Once in the top-10 shootout, he ended up six tenths adrift of McLaren's polesitter Lando Norris to underline Mercedes' struggles in higher temperatures.
"It was a total underperformance, literally from everybody involved here," Wolff told Sky Sports.
"Losing a car in Q1 is just not on - driver-team combination, it shouldn't happen. At the end, we just didn't have the pace. A very disappointing day."
Russell had questioned Mercedes' decision not to fuel the car to the end of Q1 knowing the track would ramp up as it dried, though reneged somewhat when taking responsibility over team radio on his in-lap, apologising and suggesting the failure was "on me".
And, while revealing Russell went against the initial run plan at the end of the session, Wolff conceded more fuel should have been put into the car.
"He thinks he should have had the first lap in, where Lewis went P1, he said that was probably taken too easy," explained Wolff, recounting Russell's efforts.
"The other one, we put enough fuel to the end but it was a different run plan. It was a fast-slow-fast and he decided to do three fast laps.
"But overall, it is 70% the team's mistake on not fuelling one lap more."
