After topping with Mercedes last week's post-season test in Abu Dhabi, George Russell rolled out of the Silver Arrows garage at Yas Marina on Monday morning for the final day of running in 2019.
Russell is on duty with Mercedes to conduct a second day of 18-inch wheels testing for Pirelli.
It was the German outfit's first taste of the 2021-spec wheels which were also sampled earlier this year by Renault and McLaren.
Russell was driving Valtteri Bottas' Abu Dhabi Grand Prix W10 which was specially adapted for the 18-inch test.
All the data gathered during the tests will be shared with all the teams to ensure that everyone enjoys the same knowledge moving forward.