Nico Rosberg's surprise retirement from Formula One has sent shockwaves through the sport.
The decision, taken after he won the world championship on Sunday, leaves a vacant seat at Mercedes AMG Petronas - arguably the most coveted seat in Formula One in recent history.
Mercedes chief Toto Wolff has said that no decision on Rosberg's replacement has been made as of yet.
"No, I think the first thing on the agenda was to give Nico the opportunity to tell everybody that he is retiring," he said when asked about a replacement. "We did not want it to be leaked so we kept it in a very small circuit."
“Obviously now, we had to consider all options and it will be very hard,” he added. "We are going into a new era of technical regulations and there is a free Mercedes cockpit for the seasons ahead."
“We will take the necessary time to evaluate our options and then find the right path for our future.”
But who will replace the champion? We take a look at the prime candidates.
An early front runner, Wehrlein has been a Mercedes test driver since 2014 and has undertaken most of the team's 2017 Pirelli tyre testing. In fact, Wehrlein has more 2017 tyre mileage under his belt than any other driver, giving him a unique advantage.
After serving his F1 apprenticeship with Manor this year, scoring the team's only point, the 2015 DTM champion was overlooked by Force India in favour of fellow Mercedes tester Esteban Ocon. But could Rosberg's shock exit give this youngster's career a kickstart?
Another highly-rated Mercedes junior - Ocon began the year racing for the marque in DTM and testing for Renault as part of a loan agreement between the two teams. He ended the year racing for Manor in F1 and holding a contract to race with Force India in 2017. However, could Mercedes rip up that contract and snatch back the Frenchman, leaving Wehrelin at Force India? Possibly...
Valtteri Bottas has the luxury of being managed by Toto Wolff, the boss of Mercedes Motorsport and the man at the helm of their F1 team. He also drives for a Mercedes customer team in Williams. In fact, with Rosberg gone and Nico Hulkenberg on his way to Renault, he is arguably one of the highest rated Mercedes-powered driver in the field, behind only Lewis Hamilton, and perhaps Sergio Perez.
Williams recently signed the Finn onto a new contract but this unique situation could lead to Mercedes breaking out their chequebook. to lure the ex-GP3 champion away.
Two-time champion Alonso has made no secret of his desire to make the jump to Mercedes, should the possibility ever arise. Now it has, but the Spaniard still has one year left on his McLaren contract. Stranger things have happened. The question them would be, who would replace Alonso?
Bear with us here...Niki Lauda, Alain Prost, Nigel Mansell, Michael Schumacher; a number of world champions have walked away from Formula One, only to find that their competitive desire still burns and they make a return a few years later. Could Rosberg's replacement be a short term one until he returns? Could Rosberg take Lewis Hamilton's place when his contract expires at the end of 2018?