Novak Djokovic was warned for unsportsmanlike behaviour during his opening win over Austria’s Dominic Thiem in the ATP World Tour Finals in London on Sunday.
The Serbian world No 2 smacked a ball angrily towards his backroom staff seated courtside after losing the first set on tie-break that fortunately went over them and into an area that contained no seating.
It was the third instance this year that Djokovic has lost his composure on the
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