The seven-time champion was hoping to defend the title he won last year
Novak Djokovic has pulled out of tennis' season-ending ATP Finals due to ongoing injury problems.
The seven-time champion was hoping to defend the title he won last year.
Djokovic's season is now over - with the highlight being the career Golden Slam he achieved by winning gold at the Paris Olympics.
In the women's competition today in Riyadh, Iga Swiatek takes on Coco Gauff and Jessica Pegula faces Barbora Krejcikova.