Mercedes boss Toto Wolff has revealed that the team will begin hunting for Nico Rosberg's replacement on Monday after the world champion announced his shock retirement.
The 31-year-old claimed his maiden title just five days ago after earning a podium finish in the Abu Dhabi Grand Prix.
Rosberg missed out on winning the crown in the 2014 and 2015 seasons as his teammate Lewis Hamilton, with whom he has had a tumultuous relationship, dominated on the track.
The attention now turns to Rosberg's replacement, with Fernando Alonso and Sebastian Vettel being touted as potential options, while Mercedes junior Pascal Wehrlein could be in contention after completing his first season in F1.
During an FIA news conference, which was broadcast live on Facebook, Wolff said: "Now we have to consider all options. It will be very hard to replace him. We will start to look at this on Monday."
When asked if he predicted Rosberg's retirement, Wolff replied: "No. It was difficult to know something was going on, it took me completely by surprise. Equally in the same way it causes admiration."
During his 10-year career in F1, Rosberg won 23 races, nabbed 57 podium positions and claimed pole on 30 occasions.