Championship leader Kimi Antonelli has said he felt "empty" after retiring from second place at the Barcelona-Catalunya Grand Prix and losing 18 points in the title fight.
The 19-year-old Mercedes driver saw his lead in the standings cut from 66 points to 41 after his closest rival, Lewis Hamilton, went on to take his first win with Ferrari on Sunday.
Antonelli had just overtaken teammate George Russell for second place when his Mercedes suffered an "electrical shutdown" with four laps remaining.
"I didn't see it coming," Antonelli said. "All of a sudden, I was at the apex of Turn 5 and the car gave up. It is what it is: part of racing. Nothing we can do about it.
"Of course, there's a bit of concern because we've had several issues so far in the year. It's a point that we need to work on because losing so many points in this kind of races, it hurts.
"But, of course, I feel very empty emotionally right now, because we're trying to soak in what has just happened. So, I need to travel with a head high because the pace was good and I think, you know, I'm already looking forward to Austria because I think we can do really well."
The power unit failure came just two races after Russell suffered a similar issue at the Canadian Grand Prix that forced him into retirement.
Mercedes' engine customer team, McLaren, has also suffered multiple issues this year and team principal Toto Wolff said it was vital the issues are fully understood.
"We don't know yet what was the cause of the failure," Wolff said. "Most of the others were battery related, but different failures. It was not always the same. So we need to understand what it was.
"But clearly, the symptom was quite similar, like George in Montreal, where the car just switched off. But, you know, we will be really digging deep to make sure that this doesn't happen again."
Wolff added: "I'm underwhelmed. We can't DNF cars in a kind of regular, continued way.
"Losing 25 points the constructors' championship in Montreal and losing another 25 points, or 18 points today, in order to finish first, first you have to finish. And reliability, this is what we need to get on top of. And that's number one.
"So nobody is happy about that. And we will leave no stone unturned to understand."
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After starting third on the grid, Antonelli passed teammate Russell for second place one lap before he retired from the race.
Antonelli came close to passing Russell earlier in the race and said the battle with Hamilton over the lead could have been closer had he made a move stick.
"We had a really strong pace, I think," Antonelli said. "I had one opportunity [to pass] in stint two as well, and if I get that opportunity and it can be a different race.
"Today was really hard to follow because it was so warm, the tyres were overheating so much, and the tyre was just sliding when staying close to the car in front.
"So, it was hard to manage, but we had a really strong pace and once I got the opportunity, I went for it.
"Of course, it was a shame that the issue happened with so little laps remaining, I think it was three or four, but that is what it is, part of racing. And now we focus on to the next one."
