Mercedes Technical Director Mike Elliott believes the team's weather radar was crucial to their race-winning strategical call for Lewis Hamilton at the end of the Russian Grand Prix.
A late rain shower caused chaos during the final five laps in Sochi as Hamilton tried to close in on Lando Norris to make an overtake.
Having initially ignored the team's call to pit, Hamilton switched to the Intermediate tyres on Lap 49 whilst Norris only pitted two laps later, which cost him the victory. The decision gave Hamilton his 100th win in Formula 1.
"I think the reality in these situations is really, really difficult for the strategists to get it right," said Elliott.
"With Lewis, we knew we were in second in the race and we knew if we got that wrong we could fall right back down in the field. So it is a much more challenging call [than Valtteri Bottas'].
"But the strategists are looking at lots of different bits of information. They are looking at the timing from each sector and trying to work out are we going to transition between slicks and Intermediates?
"They get the information fed into them about the weather from the weather radar and they are also listening to the driver feedbacks and the drivers telling them how they feel the circuit is like.
"So that position, we got a half-dry circuit, a half wet circuit. It is a really difficult call to make, probably one of the most difficult things for the strategists to do."
McLaren believed the rain intensity was going to remain the same during the final four laps, whilst Mercedes told Hamilton they expected the rain to increase, which pushed them into making a pit-stop.
Elliott confirmed the Mercedes team member who was looking at the weather radar was pivotal for Hamilton's win.
"The bit that really made the difference for us was the weather radar and the person that was looking at the weather radar made a very clear call," continued Elliott.
"What they said is they expected more rain before the end of the rain, the track was actually going to get wetter, and that's what tipped the balance to the decision of pitting for the Intermediates."
Lewis Hamilton claimed his 100th Grand Prix win to move into the championship lead, but it's Red Bull and Max Verstappen who will be happiest after the Russian Grand Prix.