World No. 4 Holger Rune has crashed out of the US Open in the first round, suffering a shocking four-set loss to Roberto Carballes Baena.

World No. 63 Carballes Baena ousted Rune in four sets, winning the match 6-3, 4-6, 6-3, 6-2 to progress through to the second round of the New York major.

It was a shaky start for the 20-year-old as he dropped the first set. However, he seemed as though he was turning things around when he won the second set 6-4, and many fans assumed things could only improve for the Dane from then on. Unfortunately for him, the very opposite was about to happen.

Things initially looked promising for the young player as he broke Carballes Baena to get back on serve at 3-4 in the third set.

However, he then proceeded to lose the next eight points, which signaled the beginning of the end for Rune's 2023 US Open run.

While the fourth seed was returning at 4-2 in the fourth set, a double fault gave Carballes Baena a golden opportunity of three break points, but the Spaniard only needed one to get ahead of Rune.

Overall, Rune committed forty-one errors during the match, helping an on-form Carballes Baena to a place in the second round where he will face either Aslan Karatsev or Jiri Lehecka in the next round.

This defeat comes after Rune had a difficult run on the North American swing. He lost his opening round at the National Bank Canadian Open earlier this month before retiring from the Cincinnati Open with a back injury.

Moreover, Rune has been involved in a court allocation controversy at the US Open over the last few days, after he took a dig at the tournament organizers for putting him on Court 5, the fifth most important court, as the fourth seed. Some fans were equally shocked at the allocation, while others complained that he should just get on with it.

Now, Rune will not get the chance to play on any more courts at this year's American Slam, but Carballes Baena will no doubt be aiming for a deep run at the tournament now that he has dispatched one of the top seeds.