No. 4 Rune stunned by Carballes Baena in 1st round of US Open

Holger Rune is the first big name to fall on the men's side at the US Open.

The World No. 4 lost 6-3, 4-6, 6-3, 6-2 to Roberto Carballes Baena in his first-round matchup in New York.

It was the Spaniard's first career victory against a top-10 player.

"Disappointing day today," Rune told reporters postmatch, according to the ATP. "I had, as you know, a setback after the tournaments in Toronto and Cincy, where I had to retire. Not the best preparation I had.

"Not satisfied with the result, obviously, but also with my tennis. There is only one way, and it's to work."

Rune hasn't won a match since reaching the quarterfinals at Wimbledon last month. The 20-year-old's serve was broken seven times and he committed 43 unforced errors.

Carballes Baena will take on Aslan Karatsev in the next round.