Spanish teenager Carlos Alcaraz claimed his maiden Grand Slam title at the US Open on Sunday and became the youngest man to ascend to the world number one ranking.
The 19-year-old dragged his weary body to a 6-4, 2-6, 7-6 (7/1), 6-3 victory over Norway's Casper Ruud in the final.
Alcaraz, the first teenager to claim the top ranking, is the youngest Grand Slam men's champion since Rafael Nadal at the 2005 French Open after a performance which yielded 55 winners and 14 aces.
On a day of landmarks, he is also the youngest champion in New York since Pete Sampras in 1990.
"This is something that I dreamt of since I was a kid -- to be number one in the world, to be a champion of a Grand Slam," said Alcaraz.
"This is something that I worked really really hard for. It's tough to talk right now, a lot of emotions.
"This is something that I tried to achieve, all the hard work that I did with my team and my family. I'm just 19 and all the top decisions were taken by my parents and my team. This is something that is really, really special for me."
It was a gruelling tournament for Alcaraz who also claimed the record for most time spent on court at a single Grand Slam event, passing the 23 hours and 21 minutes it took Kevin Anderson to finish runner-up at Wimbledon in 2018.
Most of his 23 hours and 40 minutes were taken up by the more than 13 hours it took him to play three successive five-setters to reach the final.
He had to save a match point in his five-hour 15-minute quarter-final win over Jannik Sinner.
Nadal was quick to congratulate the player widely seen as his heir apparent.
"Congratulations @carlosalcaraz for your first Grand Slam and for number 1, which is the culmination of your great season, which I am sure will be many more," tweeted the 22-time Slam title winner.
Defeat for Ruud, who was also vying for the world number one ranking, was his second in a Slam final this year after he was routed by Nadal in the French Open.
"Today was a special evening for both Carlos and I. We knew what was at stake, and I think it's fitting both finalists will be number one and number two in the world," said Ruud.
"I'm happy with that number and I will continue to chase that ranking and my first Grand Slam."
With the roof closed, the Arthur Ashe Stadium crowd observed a moving moment's silence on the 21st anniversary of the September 11 attacks before the final got off to a tentative start.
Both men saved break points in their opening service games before Alcaraz gained the only break of the first set for a key 3-1 lead.
Ruud dropped the set but triumphed in terms of sportsmanship when he called a double bounce on himself in the eighth game, conceding the point to the Spaniard.
Alcaraz served it out to love and a one set lead courtesy of his 13 winners to six for the Norwegian.
The Spanish teenager, who went into the final with a 2-0 winning record over Ruud, squandered a break point at 2-2 in the second set.
Ruud made him pay, edging ahead for 4-2 and then levelling the final on a second set point after another careless Alcaraz drop-shot opened the court invitingly for the Norwegian.
At that moment, Alcaraz had been on court at the tournament for almost 22 hours, passing the mark set by Andy Murray when the Briton claimed the 2012 title.
He was ahead for 2-0 in the third set before Ruud hit back.
The 23-year-old Norwegian had two set points in an 11-minute 12th game but was unable to convert as Alcaraz put away inch-perfect, back-to-back volleys.
Alcaraz made the most of his reprieve, racing through to his first tiebreak success of the tournament as Ruud's game fell suddenly apart.
The Spaniard sensed his chance, breaking for 4-2 in the fourth set before taking his aces count to 12 to lead 5-2.
Ruud held to love but Alcaraz claimed his slice of history on a second match point before collapsing to the court in celebration.