Carlos Alcaraz slumped onto the blue hard court and slapped his face in overwhelm - despite a world-class performance, Jannik Sinner was nothing but pure disappointment: after a sensational comeback victory, the exceptional Spanish talent is only two more successes from the first Grand Slam coup and the leap to the top of the world rankings.

The 19-year-old Alcaraz decided a quarter-final at an absolutely world-class level against the Italian with 6: 3, 6: 7 (7: 9), 6: 7 (0: 7), 7: 5, 6: 3 in 5:14 hours to yourself.

At 2:50 a.m. local time, he converted the match point with an ace - later a match at the US Open had never ended.

"I don't know how I did it," said Alcaraz: "I always believe in myself.

The match was at an incredible level.”

Alcaraz' dreams are still intact.

So far, his record at majors has been reaching the quarterfinals – both in New York last year and in Paris this summer.

Now, thanks to his outstanding fighting qualities, on Friday in a duel with crowd favorite Frances Tiafoe from the USA, it's about reaching the final.

The 24-year-old had previously torn the audience from their seats and continues to enchant New York with his power tennis.

"It's really wild, it's crazy," Tiafoe said after beating Russia's Andrei Rublev: "Two days ago I managed the biggest win of my career and now I'm in the semifinals."

First American to reach semifinals since Andy Roddick

In the round of 16 he sensationally knocked out Grand Slam champion Rafael Nadal (Spain), now he followed up with a cool 7: 6 (7: 3), 7: 6 (7: 0), 6: 4.

Tiafoe is the first American to reach the semifinals of the US Open since Andy Roddick in 2006.

And dreams of more, which also applies to Casper Ruud.

The Norwegian is still Alcaraz's opponent in the race for number one.

He meets the Russian Karen Khachanov in the semifinals.

First of all, the women are required on Thursday - and here, too, the outcome seems open.

The world number one Iga Swiatek prevailed in her quarter-final match 6: 3, 7: 6 (7: 4) against the American Jessica Pegula and is among the top four for the first time in New York.

But the Pole, who eliminated Jule Niemeier (Dortmund) in three sets in the round of 16, did not seem untouchable and is challenged by Aryna Sabalenka.

The Belarusian won against the Czech Karolina Pliskova 6: 1, 7: 6 (7: 4).

"I will work towards maintaining my focus and determination," Swiatek said.

Before that, the in-form Frenchwoman Caroline Garcia and the Wimbledon finalist Ons Jabeur meet.