Djokovic lost to Alcaraz in the US Open 2025 men's singles semis
The Serbian claimed he 'ran out of gas' eventually
Alcaraz prevailed 6-4 7-6 (7-4) 6-2 in two hours and 23 minutes
Novak Djokovic conceded he "ran out of gas" and struggled with the "physicality" of his US Open semi-final defeat by Carlos Alcaraz.
The 24-time major winner bowed out at Flushing Meadows in straight sets, as Alcaraz prevailed 6-4 7-6 (7-4) 6-2 in two hours and 23 minutes at Louis Armstrong Stadium.
Djokovic had kept pace with the Spaniard, who is 16 years his junior, but the age gap was evident when he fell two sets behind, with the 22-year-old's energy levels too much for him to handle.
The Serbian has now lost all four major semi-finals he has contested in 2025, becoming only the second player to do so in a single season during the Open Era, 30 years after Conchita Martinez.
And the 38-year-old acknowledged he finds it more difficult to keep up with the likes of Alcaraz and 24-year-old world number one Jannik Sinner.
"I'm happy with my level of tennis, but it's just the physicality of it," Djokovic said.
"As I said after the quarter-finals, I'm going to do my very best to get my body in shape to sustain that level and rhythm for as many hours as it's needed, but it wasn't enough. That's something, unfortunately at this point in my career, I can't control.
"I can only do as much as I can do. It will be very difficult for me in the future to overcome the hurdle of [Jannik] Sinner or Alcaraz, in the best-of-five at the Grand Slams. I think I have a better chance in best-of-three, but in best-of-five, it's tough.
"I lost three out of four Slams in semis [in 2025] against these guys [Alcaraz and Sinner], so they're just too good, playing at a really high level.
"Unfortunately, I ran out of gas after the second set. I think I had enough energy to battle him and to keep up with his rhythm for two sets. After that, I was gassed out, and Alcaraz kept going."
Defeat saw the end to Djokovic's latest quest for what would be a record-breaking 25th Grand Slam, moving him ahead of Margaret Court.
Nevertheless, he is determined to keep fighting at the bigger tournaments, and trying to compete with the next generation.
"It's expected that the young guys are improving. These two players [Sinner and Alcaraz] are the best in the world right now," he added.
"If you're not improving, then something is not right, so you have to adapt to that and make changes.
"But they seem to have a very good team, a very good strategy of training, and approach to the tennis world. The results are a testament to that. So, there is no doubt that they are better and better each year.
"Of course, it's frustrating on the court when you are not able to keep up with that level physically, but at the same time, it's also something expected, I guess. It comes with time and with age.
"I still enjoy the thrill of competition. Today, I received amazing support again on the court from the crowd. [I am] very thankful for that.
"I thoroughly enjoyed myself. That's one of the biggest reasons why I keep on going. The love that I've been getting around the world has been amazing the last couple of years."
