Tennis great Roger Federer posted a video on Twitter and followed up with a challenge for cricketer Virat Kohli.
Federer posted a 'solo drill' as part of his home training routine.
It involved bouncing a ball off a wall with a racquet.
He challenged a host of celebrities and sportspersons to share their home training routines.
Apart from Kohli, the others included footballers like Cristiano Ronaldo, basketball players like Stephen Curry, actors like Hugh Jackman, and even businessman and philanthropist Bill Gates.