The world's top eight male tennis stars are in London this week for the ATP World Tour finals, so what better way to warm up than with a challenge.
They've taken on the 'mannequin challenge' together, trying to stay still.
The latest craze is seeing people take videos of themselves standing completely still - like mannequins in a shop window.
Novak Djokovic starts Sunday's play against Dominic Thiem from 2pm on BBC Two.
Pictures courtesy of ATP World Tour.