2018 US Open – Men's singles

Novak Djokovic defeated Juan Martín del Potro in the final, 6–3, 7–6^(7–4), 6–3 to win the men's singles tennis title at the 2018 US Open. It was his third US Open title and 14th major title overall.

Rafael Nadal was the defending champion, but he retired in the semifinals against del Potro in a rematch of the previous year's semifinal. Nadal and Roger Federer were in contention for the world No. 1 singles ranking; Nadal retained the top ranking after Federer lost in the fourth round.

This tournament marked the last major appearance of former world No. 3 David Ferrer; he retired from his first round match against Nadal due to injury. This was also the first major since the 2017 Wimbledon Championships in which former world No. 1 Andy Murray participated, entering with a protected ranking. He lost in the second round to Fernando Verdasco.

This marked the first time in the tournament's history that seven former champions competed: Federer, del Potro, Nadal, Djokovic, Murray, Marin Čilić and Stan Wawrinka.

Peter Polansky was the first player to qualify for the main draw of all four majors as a lucky loser in a calendar year.