Novak Djokovic defeated American Sebastian Korda 6-3, 7-6(7-4) on Thursday to set up a semi-final meeting with Grigor Dimitrov. In the process, the 24-time Grand Slam champion became the oldest player to reach the last four in a Masters 1000 event.

Czech teenager Jakub Mensik marched into his first Masters semi-final in Miami on Thursday when he defeated France's Arthur Fils 7-6 (7/5), 6-1. Fourth-seeded Novak Djokovic also took his place in the last four with a 6-3 7-6 (7/4) win over American Sebastian Korda.

Watching Djokovic has become a live-action demonstration of a tennis player figuring out his limits from match to match and week to week.