In the third round of the US Open, Alexei Popyrin surprised Novak Djokovic with an upset victory.

On Friday night at the U.S. Open, Novak Djokovic, one of the greatest tennis players of all time, was disappointed after losing in the third round to 28th-seeded Alexei Popyrin of Australia with a score of 6-4, 6-4, 2-6, 6-4.

Djokovic lost just one night after Alcaraz, the favorite to win the U.S. Open, was defeated in the second round.

"Djokovic stated that the match was not suitable for him as he was not performing at his best. He explained that it is not good to be physically fit and motivated to play in a Grand Slam but unable to find one's game. He concluded that the game was falling apart, and tournaments like this happen."

Djokovic aimed to be the first tennis player with 25 Grand Slam singles titles, but he went a year without winning a major championship for the first time since 2017. This was the first time since 2010 that he finished a year without a major championship.

For the first time since 2002, none of Djokovic, Nadal, or Federer won a Slam trophy this season.

At Flushing Meadows, Djokovic's third-round exit is his worst performance, with the only other times he was defeated that early being in 2005 and 2006.

He has won the title at Arthur Ashe Stadium a total of 4 times, in 2011, 2015, 2018, and 2023.

After winning his first Olympic gold medal for Serbia, he double-faulted 14 times and appeared physically sluggish and emotionally flat on Friday.

"Clearly, winning the gold had an impact on me," Djokovic stated. "Although I arrived in New York without feeling mentally and physically fresh, I decided to give the U.S. Open a try and do my best. I didn't experience any physical problems, but I simply felt drained. This was evident in my play."

Popyrin will attempt to reach his first Grand Slam quarterfinal after defeating Djokovic, as he looks to defeat No. 20 Frances Tiafoe, who outlasted No. 13 Ben Shelton in an all-American match that lasted 4 hours, 3 minutes on Friday evening.

"Djokovic stated that if Popyrin serves and plays well, he can defeat anyone. He added, "Alcaraz is out, I'm out, and there are some big upsets. The draw is now open.""

The Associated Press contributed to this report.