Novak Djokovic becomes oldest Masters semi-finalist in Miami

The 37-year-old Serb made a strong start against Korda, breaking early to get a first set advantage that he never let slip but Korda showed great resilience in the second set, taking the contest to a tie-break.

But the fourth seed, looking for his seventh Miami Open title but first since 2016, again came up strong, sealing the win with a powerful ace.

Djokovic, who will face Bulgarian Grigor Dimitrov on Friday, had no doubt what had been the key to his success after winning 84% of his first-serve points.