The weather could prove to be a crucial element in today's Brazilian Grand Prix.
If Nico Rosberg wins today, he will be crowned world champion for the first time.
But Mercedes chairman Niki Lauda isn't overly concerned, with Mercedes having already wrapped up the constructors' title.
"The weather for tomorrow does not look so great," he said. "Everything can change."
But Lauda insisted that Rosberg will be able to handle whatever is thrown at him.
"Nico will go to sleep tonight," Lauda said late on Saturday. "Tomorrow he gets up, looks at the weather, and then will start to think about how the race might develop."
Lauda also revealed that after qualifying that he and Toto Wolff were split on who they thought would be on top on Saturday.
"Toto and I only made a bet about which of our cars will be ahead," Lauda told German television RTL after qualifying.
"I said it will be Lewis, Toto said Nico. So I was right."
Rain is currently falling at Interlagos but leading F1 journalist Will Buxton has revealed that so far, there are no plans to start the race behind the safety car.
"Just spoke to Charlie Whiting," he said on Twitter. "If weather stays as it is, normal race start. Good grip. No standing water. No need for Safety Car."
Just spoke to Charlie Whiting. If weather stays as it is, normal race start. Good grip. No standing water. No need for Safety Car.— Will Buxton (@thebuxtonblog) November 13, 2016
Bahrain International Circuit - Winter testing