Jannik Sinner and Carlos Alcaraz navigated through shaky starts in the first round of the US Open on Tuesday, setting the stage for a potential semifinal encounter. World No. 1 Sinner rallied from a set and a break down to overcome Mackenzie McDonald, ranked 140th, in his first appearance since a doping test scandal. Alcaraz, the third seed and reigning champion in New York, shook off a hiccup in the second set to dispatch Australian qualifier Li Tu, ranked 186th, 6-2, 4-6, 6-3, 6-1. Sinner, from Italy, secured a hard-fought 2-6, 6-2, 6-1, 6-2 victory over McDonald at Arthur Ashe Stadium, dominating the latter part of the match by winning 18 of the last 22 games. The 23-year-old returned to the court just a week after news broke of his failed drug tests in March, but he avoided a lengthy suspension as officials ruled he was not responsible for the presence of the banned substance clostebol.

"The support from the fans has been tremendous, even after the news broke, and I felt it during practice sessions as well," Sinner commented. "It's still a bit challenging. You just have to take it day by day." Alcaraz, who claimed his first Grand Slam title in New York in 2022, faced Tu in the night session, with Tu yet to win a main tour match this year. Despite a strong start from Tu, who aimed to upset a player vying to become the third man in the modern era to win the French Open, Wimbledon, and US Open in the same year, Alcaraz quickly regained control, extending his Grand Slam winning streak to 15 matches. "He caught me off guard a bit. He was nervous at first but then played some excellent tennis," Alcaraz remarked.

Fifth seed Daniil Medvedev, who thwarted Novak Djokovic's bid for a calendar Grand Slam by winning the 2021 US Open, advanced with a four-set win over Dujan Lajovic. Meanwhile, 2016 champion Stan Wawrinka was unable to become the third man in the past 50 years to win a main draw match at the US Open at age 39 or older, falling to Italian qualifier Mattia Bellucci 6-4, 7-6 (7/5), 6-3. In the women's draw, former champions Bianca Andreescu and Emma Raducanu were eliminated, with Andreescu losing to sixth seed Jasmine Paolini and Raducanu falling to Sofia Kenin, the 2020 Australian Open winner. Britain's Dan Evans triumphed over 23rd seed Karen Khachanov in the longest match in US Open history, a grueling five-hour, 35-minute marathon.