World number one Jannik Sinner’s Cincinnati Open title defense remains on track after a dramatic and hard-fought victory over Canada’s Gabriel Diallo on August 12, 2025. In a match that had just about everything—towering serves, a tense tiebreak, and even a fire alarm—Sinner dug deep to prevail 6-2, 7-6(6), booking his place in the last 16 and keeping his remarkable unbeaten run on hard courts alive.
This was Sinner’s first tournament since his Wimbledon triumph over Carlos Alcaraz in July, and expectations were sky-high for the 23-year-old Italian. He opened his Cincinnati campaign with a commanding 6-1, 6-1 victory over Daniel Galán, but things got far trickier against Diallo, who has emerged as one of 2025’s breakout stars. The 6ft 8in Canadian, now ranked a career-high No. 35 after starting the year outside the top 80, brought his booming serve and fearless attitude to Center Court, determined to make an impression in his maiden face-off with the world’s top player.
From the outset, it was clear that Diallo would not be overawed. In fact, he broke Sinner’s serve in the opening game of the match, capitalizing on a rare double fault from the Italian. But Sinner, ever the competitor, immediately responded by breaking back at love, then rattling off three consecutive breaks to take the first set 6-2 in just 50 minutes. Diallo’s serve, while potent—he fired 10 aces—was also erratic, as he committed a career-high 10 double faults and faced 12 break points, three of which Sinner converted in that opening set.
“It was a tough match, it felt like a very difficult day in the office. I think he served unbelievably all the time, but especially in the second set,” Sinner admitted after the contest. The Italian’s ability to handle adversity was tested not just by Diallo’s power but by the conditions themselves. The match, originally scheduled for the afternoon, was delayed by a 75-minute power cut that knocked out the TV feed and electronic line calling at the venue. When play finally began, the drama was far from over.
The second set saw both players settle into their games, holding serve and trading blows from the baseline. Diallo, eager to prove he belonged on the big stage, elevated his level, saving break points and matching Sinner winner for winner. The Canadian’s forehand, however, betrayed him at key moments—he would finish the match with 50 unforced errors, the majority from that wing.
Midway through the second set, the match took an even stranger turn. A fire alarm began to sound and lights flashed in the second game, causing a brief delay. After several minutes, both players agreed to play through the distraction, a decision that only added to the tension on court. “You have to find the balance against these big servers. I struggled with that at times today,” Sinner reflected, acknowledging both the quality of his opponent and the unusual circumstances.
The set remained on serve all the way to a tiebreak, with the crowd on the edge of their seats. Diallo struck first, moving ahead 4-2 in the breaker and then earning a set point at 6-5 after some aggressive play. But Sinner, showing precisely why he sits atop the ATP rankings, saved the set point with a brilliant return that landed flush on the baseline. He then took advantage of a Diallo volley error to grab a match point at 7-6, and sealed the victory with a powerful serve—his composure under pressure once again on full display.
“In the end, this is what I was looking for, I need matches as tough as this, being immersed in adverse situations during the game,” Sinner told reporters, emphasizing the importance of grinding out wins as he builds toward the US Open later this month. “But I need tough matches like this, I’m happy I got one before the [US Open] Grand Slam.”
Despite the straight-sets win, Sinner was not entirely satisfied with his performance. He was seen heading straight back onto the practice courts after the match, determined to iron out the issues that troubled him against Diallo. “Now I have to prepare for a new challenge for the next round knowing that conditions will again be very difficult, so I can only have a strong mentality, accepting certain situations that will occur on the court,” he explained, referencing the unique conditions in Cincinnati. The Italian noted that the ball “flies a lot” during the day but “maybe at this time it is noticeable a little less” at night, highlighting the adjustments required as the tournament progresses.
For Diallo, the loss was a disappointment, but his performance confirmed his growing status on the ATP Tour. Having claimed his first title earlier in the year and steadily climbed the rankings, the 23-year-old Canadian showed he can compete with the world’s best. Sinner was quick to praise his opponent’s efforts, noting, “He was serving very well, especially in the second set… If you don’t play well in tough situations like this you can lose these matches.”
The win extends Sinner’s unbeaten run on hard courts to 23 matches, a streak that dates back to earlier in the season and includes his Cincinnati title from last year. He is now on a six-match winning streak at this event and remains hungry for more. With four Grand Slam titles already under his belt in 2025—including the Australian Open and Wimbledon—Sinner is looking to add another Masters 1000 trophy to his rapidly expanding collection.
Up next for the Italian is French qualifier Adrian Mannarino, one of three unseeded Frenchmen to reach the fourth round in Cincinnati this year. Sinner knows he’ll need to be at his best to keep his title defense alive, especially with the US Open looming large on the horizon. “These matches we play at night, if we compare them with the ones we play during the day, are positive,” Sinner said, determined to adapt and thrive no matter what challenges come his way.
As the Cincinnati Open rolls on, all eyes remain on the world number one. If this gritty, drama-filled victory over Diallo is any indication, Jannik Sinner is more than ready for whatever comes next.
