The stakes could hardly be higher in the marquee meeting at the iconic Arthur Ashe Stadium, with the world number one ranking on the line and a $5 million winner's cheque awaiting, but the real prize is bragging rights in a year that has been theirs.
Spaniard Alcaraz completed a great escape against Sinner in June by saving three match points to retain his French Open trophy, before the Italian world number one responded a month later to snatch his main rival's Wimbledon crown.
"He's someone who has pushed me to the limit," said Sinner, who is aiming to become the first man to keep his crown in New York since Roger Federer won five titles from 2004-08.
"We've faced each other quite a lot now lately...
"It's great for the sport to have rivalries and have, hopefully, great matches in front of us. And then we see.
"I'm someone who loves these challenges. I love to put myself in these positions and to see how it goes."
Victory for four-time major champion Sinner will help him emulate Federer again by becoming the second man to capture both the Australian Open and US Open titles in back-to-back years after the Swiss great managed the feat in 2006-07.
Alcaraz arrives in the final seeking his sixth major crown and in sublime form, having reached the title clashes in each of the past eight tournaments he has played in, going all the way back to Monte Carlo in April.
He holds a 9-5 win-loss record over Sinner, winning six of their last seven meetings and most recently prevailing when the Italian retired in the Cincinnati final due to illness while trailing 0-5.
"I always take things from previous matches," Alcaraz said.
"The last three matches, I'm going to take note and I will see what I did wrong, what I did great in those matches, just to approach the final in a good way.
"His matches are really demanding physically. He's able to play at 100% for two, three or four hours, and I think that's the biggest improvement he has made in the last few years.
"For me, I think the consistency and not having the ups-and-downs in the matches."
There was an air of inevitability in New York about another finale featuring the two new torch-bearers of the men's game in the year's last Grand Slam, almost as if the season had been building toward this very moment.
They had given fans at Flushing Meadows an early taste of the rivalry when Alcaraz battled past Sinner in five sets in the 2022 quarter-finals en route to winning the title and taking the top ranking for the first time.
A battle between flair and precision
Alcaraz, the magician, has danced through the draw in the last fortnight with flair and imagination, conjuring winners at will from impossible angles and refusing to drop a set during his entertaining march.
The machine-like Sinner has motored his way through with relentless precision, grinding down opponents with metronomic baseline hitting and ice-cold efficiency to make the final on Sunday the ultimate clash of playing styles.
Whatever happens in the showdown, the dominant duo of men's tennis will have lifted nine of the last 10 Grand Slam trophies between them and shut out 2023 New York champion Novak Djokovic at the majors for the second straight year.
"These two players are the best in the world right now," said 24-times Grand Slam champion Djokovic after his bruising semi-final defeat by Alcaraz.
"They seem to have very good teams, very good strategy of training and approach to tennis. The results are a testament to that. There's no doubt they're better and better each year.
"That's also expected. It's nothing unusual."