Roberto Carballes Baena has pulled off a major upset at the US Open…

The 30-year-old Spanish tennis player, ranked No. 63 in the world, downed No. 4 seed Holger Rune 6-3, 4-6, 6-3, 6-2, on Monday at Flushing Meadows for his first-ever victory over a top-10 player.

Rune, a 20-year-old Dane who cracked the top 5 after reaching the quarterfinals of the French Open and Wimbledon, had complained before the match about being assigned to one of the outer courts, sarcastically posting a map of Flushing Meadows on X, formerly known as Twitter, to help his fans find it.

“I just didn’t expect to play on that court,” Rune said afterward. “That’s obviously disappointing but not going to blame the court on the loss.”

Rune suffered early exits from tuneup events in Toronto and Cincinnati and there were early signs of trouble on Monday as he failed to earn a break point in the first set.

Carballes Baena converted on break point chances in the fifth and ninth games, but his serve lost its firepower in the second set, when Rune finally broke in the third game.

Carballes Baena, who won in Marrakech earlier this year, cleaned up his act in the third set, when he broke Rune to love in the eighth game, and had clear control over the match in the fourth set, when he dropped only a single first-serve point.

The tournament lasts two weeks and wraps up with the women’s singles final on September 9, and the men’s singles final on September 10.