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Former world number one Djokovic started brightly and took control of proceedings thanks to a break of the Del Potro serve at the first time of asking to open up a 2-0 lead.
The Serbian then proceeded to win the next three games in succession and while Del Potro was able to get his first mark on the board, he was unable to prevent his opponent from wrapping up the first set in just 35 minutes.
However, the 2009 US Open champion responded positively to going behind in the second set and having broken Djokovic early on, he pressed home his advantage with a string of powerful forehand strokes.
The Argentine eventually served out for a 6-3 success, which in turn sent the contest into a deciding third set.
Service games were traded throughout the set and even when Djokovic had two break points to claim the championship at 5-4 in front, Del Potro held firm to save both.
It meant that a tie-breaker was required to determine who would come out on top. A mini-break apiece during the opening exchanges cancelled each other out, but a powerful cross-court forehand winner from Djokovic soon after handed him a 4-2 lead.
From there, he grabbed a foothold in the breaker and eventually won through 7-3 in two hours and 35 minutes.