World number one men's tennis player Novak Djokovic defeated world number four Alexander Zverev in the US Open 2021 semi-final to reach his 31st Grand Slam final. The 34-year-old Serbian won the match 4-6, 6-2, 6-4, 4-6, 6-2 in three hours and 33 minutes. Djokovic is now one victory away from a 21st major and a calendar-year Grand Slam.