Valtteri Bottas was nursing "pretty severe" front tyre damage as he held off Sebastian Vettel to secure his first Formula 1 win in the Russian Grand Prix, says Mercedes.
Bottas had dominated the early stages of the race at Sochi and appeared in control at the front when he suffered a major lock-up into the Turn 13/14 complex near the end of the lap.
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Mercedes motorsport boss Toto Wolff said the team's data revealed a worrying tyre situation after that, leading to an intense finish as Vettel's Ferrari closed in.
"He locked both front tyres and flatspotted them, and our metrics showed that it was pretty severe damage to the tyres, which harmed his performance at the end," Wolff said.
"It was a bit of a stressful moment, but he kept it together.
"You could see the pace was still good enough. Sector one was obviously very good, but in sector two he was able to fight back and there was the odd tenth he lost. But on the next lap around he was good."
Bottas explained that the lock-up happened as temperatures began to drop in his front tyres, and the moment briefly took him out of his comfort zone.
"I definitely lost some time during that lap with the flatspot," he said.
"The team was [previously] asking me to go forward with the brake bias, giving advice just to help the tyre temperatures.
"Then I had the flatspot so I had to go rearwards. I also had a little bit of traffic during that point.
"This track, it's so special about the rhythm. If you find the rhythm then you can be so quick here, and get consistent lap times and be on it.
"But if you lose it, it always takes a few laps to get it back here.
"So I kind of lost the rhythm for a bit, plus the backmarkers.
"Once I was in free air again, able to focus on my job itself, I managed to get the tyre temperatures back up and pick up the pace.
"I was also asking for a bit of radio silence from the team, for me to just to just get on with it really, for me to focus on every single corner, making it every lap perfectly, and losing minimum time with the backmarkers. And that helped."