Novak Djokovic was left furious with the umpires during his China Open quarter-final with Alexander Zverev after being on the end of what he described as the 'most stupid change of rules'.
Serb's anger boils over
The tennis icon couldn't believe his eyes as he argued with Zverev over the decision, with the incident captured live on Sky Sports.
Match context
The clash came in the quarter-final stage of the China Open, where Djokovic faced the German in a high-stakes encounter.
