Toto Wolff has apologised to George Russell after another power unit failure brought the Mercedes driver's Bahrain Grand Prix to an early end.
Russell fell 84 points off team-mate Kimi Antonelli in the F1 championship race after retiring in the closing stages in Sepang.
Mercedes suffered heartbreak on behalf of Lewis Hamilton in the 2016 Malaysian Grand Prix as his power unit went up in smoke, and the feeling was eerily similar as Russell crawled to a halt into Turn 1 in the closing stages on Sunday.
On both occasions, the failure handed a significant advantage in the championship standings to their teammate.
Mercedes had shown strong pace with a comprehensive upgrade package in Malaysia, but were overtaken in qualifying as Max Verstappen became the dominant force.
This was again the case in the race, with Ferrari also looking strong. Had Lewis Hamilton and Charles Leclerc started on intermediate tyres rather than slicks, it is likely that one or both would have battled the Mercedes drivers for podium positions.
“This has been our worst weekend of the season,” said Wolff in a statement released by Mercedes.
“It hurts, and I feel incredibly sorry for George and everyone in the team.
“George drove an outstanding race and was on course for a very strong result, but we let him down.
“The reality is that has happened too often this year, and that is not acceptable.
“We were not quick enough and we were not reliable enough in Malaysia. That is the truth.
“Both drivers kept fighting, stayed focused, and got everything out of the car that was possible though.
“Whilst George lost out through no fault of his own, Kimi did a very good job and deserved his podium.”
This was the second power unit-related retirement Russell has suffered this year, and his third retirement overall.
Antonelli too has suffered reliability problems; this causing him to miss out on a potential victory in Barcelona, while a separate problem denied him the win at Silverstone.
With the Singapore Grand Prix taking place this coming week, Wolff acknowledged that there is little time to correct things.
“Now we need to understand exactly what happened this weekend,” Wolff added.
“We underperformed compared to our nearest competitors and recent races.
“We will do so with our usual focus, working diligently and being led by the data.
“We don’t have many days before we are on track again, but we are determined to put on a better showing next week in Singapore.”
