Jannik Sinner is seeking a third Grand Slam of the season in New York
Jannik Sinner is seeking a third Grand Slam of the season in New York AFP

Jannik Sinner and Carlos Alcaraz, the world's undisputed top two players, will square off in a third straight Grand Slam final on Sunday at the US Open with President Donald Trump in attendance.

Top seed Sinner is the reigning champion and aiming to become the first man to successfully defend the US Open crown since Roger Federer won the last of five consecutive titles in 2008.

Alcaraz, who won the first of his five Grand Slam titles in New York as a teenager three years ago, is the first man in a decade to reach the US Open final without dropping a set.

It sets up a thrilling climax to a tournament preparing to host Trump, the first sitting president to attend the US Open since Bill Clinton, who watched the women's final in 2000.

It is the latest in a series of visits to major sporting events for the US leader after his trip to the NFL's Super Bowl in February and the FIFA Club World Cup final in July.

It will mark New York-born billionaire Trump's first appearance at Flushing Meadows since 2015 -- when the then-presidential candidate and wife Melania were booed on arrival by the crowd.

On the court, Alcaraz has largely had the edge over his rival of late although Sinner is enjoying one of the all-time great seasons at Grand Slams.

Only a miraculous escape act from Alcaraz, in which he saved three championship points, denied Sinner at the French Open and cost him a shot at a rare calendar Slam.

Sinner brushed off that crushing loss by beating Alcaraz in the Wimbledon final, adding to the Australian Open crown he retained in January.

The pair will collide once more inside Arthur Ashe Stadium, the scene of a 5hr 15min quarter-final classic in 2022 that has come to shape the rivalry between two generational talents.

"I feel like our rivalry started here playing an amazing match. We are two different players now, with different confidence too," said the 24-year-old Sinner, chasing a fifth major overall.

"It's great for the sport having rivalries, having hopefully great matches in front of us...He's someone who pushed me to the limit."

The 22-year-old Alcaraz ended Novak Djokovic's latest quest for a record 25th major in the semi-finals and has encountered few difficulties so far this fortnight.

He is through to his seventh Grand Slam final but is gearing up for another punishing battle with Sinner, who is riding a 27-match winning run on hard courts at the majors.

Alcaraz is 9-5 overall against Sinner and has won six of the past seven duels.

"Obviously I'm going to take things about the last matches that I've played against him," said Alcaraz.

"I'm going to take note, and I will see what I did wrong, what I did great.

"His matches are really demanding physically that he's able to play at his 100% during two, three, four hours, and I think that's the biggest improvement he has made in the last years."

The Spaniard is in a rich vein of form of his own, winning 36 of his last 37 matches. The only loss in that time came to Sinner at Wimbledon.

"I am performing at a high level and sending a message to the people on the circuit that this is my level," said Alcaraz. "It is not my maximum level, I still have room to improve, but it is a high level."

As it was when Alcaraz beat Casper Ruud here in the 2022 final, the number one ranking will again be on the line Sunday.

Alcaraz eclipsed Lleyton Hewitt's record as the youngest world number one at the age of 19, but it is two years since he last held the top ranking.

"It's a good goal, but we've tried not to focus too much on it in this tournament," said Alcaraz.

"It will remind me of the 2022 final, when I was playing for a Slam and the number one spot. It will be like a flashback. But winning a Grand Slam comes before being number one."

Carlos Alcaraz is 5-1 in Grand Slam finals. His only loss came to Jannik Sinner at Wimbledon this year
Carlos Alcaraz is 5-1 in Grand Slam finals. His only loss came to Jannik Sinner at Wimbledon this year AFP