In the dimming hours of a New York night, Alexander Zverev found himself on the brink of an unwanted slice of tennis history. The top seed at the U.S. Open for the first time in his career, Zverev was staring down the possibility of becoming the first man since 2003 to lose in the first round as the No. 1 seed at a Grand Slam. That distinction belongs to Lleyton Hewitt, who fell to Ivo Karlovic at Wimbledon over two decades ago. At the U.S. Open, no top seed had suffered such an early exit since Stefan Edberg lost to Alexander Volkov in 1990. But Zverev, showing the grit that carried him to the French Open title earlier this year, clawed his way past a relentless Lorenzo Sonego, winning 6-4, 3-6, 6-7 (7), 7-5, 6-4 in a match that ended early Wednesday morning.

The German's path to the top seed was paved by Jannik Sinner's withdrawal with a right knee injury. Zverev, who lost to Sinner in the Wimbledon final, arrived in New York with uneven form, having struggled in his previous two tournaments. Against Sonego, an Italian he had never lost to in six prior meetings, Zverev quickly discovered that past records meant little on Arthur Ashe Stadium's blue courts. Sonego, whose career mark against top-10 players in majors stood at 1-9, used his exceptional court coverage to turn potential winners into extended rallies, forcing Zverev to earn every point.

The match was a study in missed opportunities. Zverev generated 22 break points but converted only five. Sonego's serve, especially in critical moments, proved a formidable weapon. When the Italian served for the third set at 5-4, Zverev broke back, only to see Sonego rally in the tiebreaker. Zverev rocketed two serves at 133 and 141 mph to take a 7-6 lead, but Sonego won the next two points, and a double fault from Zverev handed the set to the underdog.

Undeterred, Zverev broke for a 3-2 lead in the fourth set, but Sonego immediately broke back, sprinting from corner to corner with remarkable energy. As the set progressed, Sonego moved within two points of the match at 5-4. Zverev held serve, then seized the decisive break to go up 6-5, ultimately forcing a fifth set. Before the final set, Sonego had his hand or wrist checked by a trainer, but he continued to battle. Zverev secured the crucial break for a 3-2 lead and held on to close out the marathon after nearly five hours.

"Nearly five hours for a first round, I think this is the longest first-round match I've ever played in my life," Zverev said. "So, credit to him. He played amazing tennis today, would have beaten a lot of players for sure, but I'm happy to be through."

Zverev, the 2020 U.S. Open runner-up, now advances to face Quentin Halys in the second round. Rather than lamenting the taxing effort, the German saw it as a potential turning point. "Actually I'm happy that I won this kind of battle because this exactly the match that I needed," he said. "I struggled the last two tournaments, I didn't play well and sometimes good things happen after you fight through one of these matches. So I'm hoping that will be the case for me at this tournament."

Sonego, despite the loss, demonstrated that his recent form is no fluke. His speed and clutch serving troubled Zverev throughout, and he exits the tournament with his head held high. The match, which ended at 1:22 a.m. local time, was a testament to the unpredictability of Grand Slam tennis, where even the top seeds are never safe from a determined opponent.