Halys beat Díaz Acosta 6-4, 7-5, 6-7, 6-1 at the US Open, converting four break chances and saving five of seven break points. Halys's work on return proved decisive in a match that swung in his favour after the lost third set.
Halys broke in the opening game of the first set, was pegged back at 3-3 and then broke again at 4-3 to close 6-4. Díaz Acosta went up a break to lead 3-1 in the second set, but Halys broke back at 2-3 and sealed the set with a break at 6-5. After Díaz Acosta won the third set in a tiebreak, Halys dominated the fourth, breaking at 2-0 and 4-0 to finish 6-1.
The standout number was Halys's return performance: he won 30 receiving points to 22 and broke four times. He also won 30 of 38 first-serve points (79%) and claimed six aces, while Díaz Acosta, despite a 75% first-serve rate, was hurt by losing 21 of 53 points behind that first delivery.