Watch: Djokovic suffers shock US Open defeat by Popyrin

[Nickie]

Watch highlights as defending champion Novak Djokovic is knocked out of the US Open after a 6-4 6-4 2-6 6-4 loss to Alexei Popyrin in the third round.

More... (https://www.bbc.com/sport/tennis/videos/c1epqn1v0nlo)