Roger Federer, owner of 17 Grand Slam titles, has struggled this year to replicate the high standard of success he’s set for himself over his career.

The latest loss for the Swiss great came Monday in the fourth round of the U.S. Open at the hands of Tommy Robredo, a Spaniard who had never beaten Federer in 10 attempts.

Robredo didn’t have to play the match of his life to hand seventh-seeded Federer a 7-6 (7-3), 6-3, 6-4 defeat. The No. 19 seed simply had to be the steadier man, which was stunningly easy against the man many regard as the greatest ever. Time and again Federer made ghastly errors at critical junctures, sending balls flying well past the baseline and plowing others into the net.

Liz Clarke

Federer, 32, gave credit to his opponent, but said he lacked rhythm in the match.

“I kind of feel like I beat myself, you know, without taking any credit away from Tommy,” he said. “Clearly he was making sure he was making many balls. It was up to me to make the difference and I couldn’t. I kind of self destructed, which is very disappointing.”

The loss meant that Federer would not face rival Rafael Nadal — which would have been a first at Flushing Meadows. Nadal, who has a 21-10 record against Federer, defeated German Philipp Kohlschreiber 6-7 (7-4), 6-4, 6-3, 6-1.

“Yeah, I mean, it would have been a quarters, not a final. Not that much of a disappointment at the end of the day," Federer said of not playing Nadal in the quarterfinals. “If I’m playing like this, I’m not going to beat Rafa, or Kohlschreiber, for that matter. So, for me, I didn’t think of that.”

Earlier this season, Federer lost in the second round of Wimbledon, ending his streak of reaching at least the quarterfinals of 36 consecutive Grand Slam tournaments.

The loss, to unheralded Sergiy Stakhovsky of Ukraine, dropped him out of the top four for the first time since July 2003.

Federer’s last Grand Slam title came in 2012 at Wimbledon.

“Confidence takes care of all the things you don’t normally think about,” Federer said [after the Robredo match]. “It has been a difficult last three months. My consistency is just not there.”

Liz Clarke

In attempts to remedy his slump, Federer switched to a larger racket shortly after Wimbledon. The experiment did not work — Federer lost to much lower-ranked players in two subsequent tournaments and to Nadal in the Cincinnati quarterfinals before returning to his original racket prior to the U.S. Open.

Federer reached the semifinals of the Australian Open to start the year, losing to Britain’s Andy Murray. He lost in the quarterfinals to Frenchman Jo-Wilfried Tsonga at the French Open in straight sets.

This is the first year Federer has failed to reach at least one Grand Slam final since 2002.

“The story of my life: when I lose, people are shellshocked to see me play this way. If I win, it’s the best thing,” Federer said after the Robreodo loss. “I’m trying hard out there trying to make it work. Sometimes it just doesn’t happen.”