23:55 CET - It's hard not to wonder whether that was the last time we'll see Djokovic at the US Open. He remains the third-best player in the world, but a combination of physical issues and the quality of the two above him have led to him losing every single set in the four Grand Slam semi-finals that he's contested this season.
He could still win a 25th major if Alcaraz and Sinner run into fitness problems of their own, but how long is the Serb willing to wait for that to happen?
23:45 CET - Alcaraz is into the US Open final! Djokovic's age caught up with him in the final set, with the 38-year-old completely running out of steam, and Alcaraz took advantage to seal a 6-4, 7-6, 6-2 win.
The Spaniard has often lost his concentration in such scenarios in the past, but he was focused and ruthless tonight.
23:10 CET - Alcaraz wins a titanic battle of a second set! Djokovic stepped things up massively, breaking his opponent's serve and looking much stronger on his own, but the younger man ultimately managed to fight back and take things to a tiebreak, which he won 7-4.
After just under two hours of play, Alcaraz leads by two sets, and Djokovic needs to produce one of the great miracles of his career.
22:08 CET - It's advantage Alcaraz, with the Spaniard taking the first set 6-4 in 48 minutes. He broke Djokovic's serve in the first game and then played aggressively to see things out, not facing a single break point.
Djokovic isn't playing badly, but just can't threaten his opponent's serve.
21:20 CET - Here we go! Djokovic vs Alcaraz is underway!
Follow every point of the match here.
19:40 CET - With just over an hour until they take to the court, let's have a look at the paths that Djokovic and Alcaraz have taken to the semi-finals.
The Serb has spent longer on court, with Zachary Svajda, Cameron Norrie and Taylor Fritz all taking sets off of him, but only his clash with Fritz lasted longer than three hours.
The Spaniard meanwhile hasn't dropped a single set in New York and has dispatched three of his five opponents in less than two hours, so he'll be feeling fresh tonight.
18:00 CET - Hello and welcome to Flashscore's live coverage of the US Open men's semi-finals!
It's a day that could be remembered for years to come, with the first semi-final being the one that everyone was hoping for when the draw was made, giving us another chapter in the already iconic rivalry between Carlos Alcaraz and Novak Djokovic.
It's a clash that really could go either way. Alcaraz has won 35 of his last 36 matches and hasn't yet dropped a set in New York this year, but Djokovic has won the last two meetings between the two, in the Olympic final and the Australian Open quarter-finals.
For the first time in 2025, the Serb is heading into a Grand Slam semi-final fully fit and without Jannik Sinner on the other side of the net, and he'll know that he won't get many more chances as big as this one to reach a major final and compete for a long-awaited 25th crown.
That being said, Sinner will most likely be standing in his way if he does beat Alcaraz tonight, with the world number one the heavy favourite in his semi-final clash with Felix Auger-Aliassime.
Alcaraz and Djokovic will do battle at 21:00 CET, with Sinner and Auger-Aliassime to follow.