Traditionally done in football/soccer with a ball, Djokovic takes it further and does it with only his tennis ball and his knees. This shows some light relief after the Serbian was slated to appear in Indian Wells but this was cancelled due to the Coronavirus.
He keeps the ball up for 20 hits and it makes fans wonder how the likes of Rafael Nadal and Roger Federer would get on against this challenge.
View the impressive video below:
https://twitter.com/atptour/status/1237686924875268099