US Open men's tournament arrives with Monday's fourth round promising captivating storylines as defending champion Jannik Sinner headlines the top half of the draw. After Saturday's stunning upset that saw third seed Alexander Zverev fall to Felix Auger Aliassime, the tournament's upper section has blown wide open, setting the stage for compelling encounters at Flushing Meadows. With one strong favorite and multiple players sensing opportunity, the ATP's elite face stern tests from inspired challengers riding waves of confidence into the second week.
Sinner vs. Bublik
World No. 1 Jannik Sinner survived his first genuine test of the tournament, rallying from a set down to defeat Denis Shapovalov 5-7, 6-4, 6-3, 6-3 in Saturday's third round. The defending champion faced adversity when trailing 3-0 in the third set with Shapovalov holding a break point for 4-0, but demonstrated champion's mettle by winning nine consecutive games to seize control. Sinner converted 84% of first-serve points despite the initial struggles and has now extended his hard-court major winning streak to 24 matches.
Alexander Bublik arrives as one of tennis's hottest players, carrying extraordinary momentum from a scorching summer run. The Kazakhstani has captured three consecutive titles at Halle, Gstaad, and Kitzbühel, posting a remarkable 20 wins from his last 22 matches. His Halle triumph included a stunning victory over Sinner himself, marking one of only four defeats the Italian has suffered in 2025. Bublik's serving has been devastating - he scores 12.8 aces on average which makes more than one per single game (1.03) on hard courts in the current ranking period. The 23rd seed dismantled Marin Cilic 6-4, 6-1, 6-4 in his opener before cruising past Tristan Schoolkate, then outlasted Tommy Paul 7-6(5), 6-7(4), 6-3, 6-7(5), 6-1 in a five-setter which ended up on a late night.
Their head-to-head looks very interesting, standing at 4-2, but Bublik holding last victory on grass at Halle. Sinner acknowledges the threat, noting after his Shapovalov win that Bublik "is the only other man to have won against me in 2025" besides Carlos Alcaraz. The Kazakhstani's unpredictable style, featuring underhand serves and audacious drop shots, could disrupt Sinner's rhythm. With astonighing 70 winners against Paul and 29 of 41 net points won, Bublik's all-court aggression poses unique challenges for the top seed's title defense.
Musetti vs. Munar
Lorenzo Musetti reached the fourth round when close friend Flavio Cobolli retired with a right arm injury while trailing 6-3, 6-2, 2-0. The tenth seed has been nearly flawless since dropping his opening set to Giovanni Mpetshi Perricard, demolishing David Goffin 6-4, 6-0, 6-2 in the second round. This marks Musetti's first fourth-round appearance at Flushing Meadows and his first at a hard-court major, having previously reached this stage three times at Roland Garros and once at Wimbledon. The Italian lives the best time on hard courts this year, as he entered with the record of just 7-7 in 2025 on that surface, being a clear clay-court specialist. He was supposed to be one of the earliest upsets as the 10th seed, but stood strong up to this point.
Jaume Munar has authored the surprise story of this section, reaching his maiden Grand Slam fourth round after defeating Zizou Bergs 6-1, 6-4, 6-4. The Spanish world No. 44 had gone 0-11 in second-round matches at majors before breaking through at Wimbledon this summer. His New York run includes victories over 31st seed Gabriel Diallo and Bergs, showcasing remarkable consistency from the baseline. Munar's grinding style has translated surprisingly well to hard courts - he defeated Alexander Bublik in five sets at Wimbledon and took Casper Ruud the distance at the Australian Open.
The head-to-head favors Munar with a strong 4-1, including a 2-6, 7-6, 7-5 victory on hard courts at Hong Kong earlier this year. While Musetti possesses superior variety with his single-handed backhand artistry and net skills, Munar's relentless baseline consistency could neutralize the Italian's flair. Musetti arrived in poor form on hard courts (1-5 in his previous six matches before New York), recovering very well on the big stage, but the Spaniard is definitely not written-off for making the upset, which would give him the best result of his life moving into quarterfinals.
Auger-Aliassime vs. Rublev
Felix Auger-Aliassime produced the upset which seems to be the most crucial for fates of the top half, stunning third seed Alexander Zverev 4-6, 7-6(9), 6-4, 6-4 in a late-night thriller. The Canadian saved a crucial set point at 6-7 in the second-set tiebreak, then dominated with exceptional net play, winning 24 of 27 points at the forecourt. Auger-Aliassime fired 50 winners in compare to just 35 winners, delivered 10 aces, and won 78% of first-serve points in recording his first victory over a top-5 player at a Grand Slam. The 25th seed has rediscovered the form that carried him to the 2021 US Open semifinals, defeating Billy Harris and Roman Safiullin without dropping a set before toppling Zverev.
Andrey Rublev survived a grueling five-set examination from qualifier Coleman Wong, prevailing 2-6, 6-4, 6-3, 4-6, 6-3 on Grandstand Court. The 15th seed struggled initially against the Hong Kong player who was making history as his nation's first Grand Slam match winner, but demonstrated his experience to weather the storm. Rublev had earlier defeated home wild card Tristan Boyer 6-3, 6-3, 5-7, 7-6(4) in the second round, extending his streak of reaching at least the third round at seven consecutive US Open editions.
The head-to-head looks very concerning for the Canadian, as Rublev leads there with 8 wins in 9 matches between both including the streak of 6 consecutive victories, two of those performed this year on hard and grass. Auger-Aliassime's aggressive baseline hitting and improved net play could exploit Rublev's defensive tendencies, while the Russian will look to dictate with his powerful forehand. Both players sense opportunity with the draw opening up - the winner faces a potential quarterfinal against either eighth seed Alex de Minaur or qualifier Leandro Riedi rather than the eliminated Zverev.
de Minaur vs. Riedi
8th seed Alex De Minaur advanced when Daniel Altmaier retired trailing 6-7(7), 6-3, 6-4, 2-0, with the German succumbing to exhaustion after logging over 10 hours through two five-set marathons. The Aussie has reached the fourth round for the fifth time in nine US Open appearances and remarkably joins Novak Djokovic, Jannik Sinner, and Carlos Alcaraz as the only players to reach the last 16 at eight of the past nine Grand Slams. De Minaur has been clinical despite playing all matches on outer courts, defeating Chris O'Connell and Shintaro Mochizuki in straight sets before the Altmaier's match which would most likely end up in 4 sets despite the German's withdrawal.
Leandro Riedi's fairytale continues after Kamil Majchrzak retired trailing 5-3 in the opening set with a torn intercostal muscle. The Swiss qualifier, ranked 435th in the world, becomes the lowest-ranked player to reach a major fourth round since Richard Krajicek at 2002 Wimbledon. Riedi has already banked $237,000 - nearly doubling his season earnings - after coming through three qualifying matches and stunning 19th seed Francisco Cerundolo 3-6, 4-6, 6-4, 6-4, 6-2 in a remarkable comeback. The 23-year-old is rebuilding after injuries dropped him from a career-high 117th last year.
No previous meetings exist between these two, but the ranking gulf of over 420 places tells only part of the story. De Minaur acknowledged Riedi's danger, noting "you don't make fourth round of the US Open if you're not playing good tennis" in his post-match interview on Sunday. The Swiss qualifier's fearless ball-striking and nothing-to-lose mentality could trouble de Minaur, though the Australian's supreme fitness and court coverage make him a heavy favorite to reach his third US Open quarterfinal.