The 2026 US Open men's singles tournament was defined by historic upsets, beginning with defending champion Carlos Alcaraz losing in the quarterfinals to Ben Shelton, which guaranteed a new champion and marked the 18th consecutive year a defending champion failed to retain the title. Novak Djokovic suffered a shocking first-round defeat to Mariano Navone, his earliest major exit since 2006, which dropped him out of the world's top 10 for the first time since 2018 and marked the first time since 2002 that none of the "Big Three" were ranked in the top 10. The tournament also saw world No. 1 Jannik Sinner miss a major for the first time since 2019, while lucky losers Arthur Géa and Bu Yunchaokete made history with deep runs, and Alexander Blockx became the first Belgian man to reach the US Open quarterfinals. Additionally, the event served as the final major appearance for veterans Stan Wawrinka and Gaël Monfils, who lost in the first and second rounds, respectively. With these shocking results, the tournament produced a highly unpredictable draw, setting the stage for a first-time Grand Slam finalist from the bottom half of the bracket.