Frances Tiafoe, ranked 20th in the world, advanced after Grigor Dimitrov, the 9th seed, was forced to retire when Tiafoe was leading 6-3, 6-7 (5), 6-3, 4-1.
On the other hand, Taylor Fritz, the world No. 12, battled past Alexander Zverev, ranked 4th, in a tightly contested match that lasted three hours and 26 minutes, with a score of 7-6 (2), 3-6, 6-4, 7-6 (3).