Rafael Nadal says he "played poorly" after his earliest defeat in 12 years at the Barcelona Open as he went down in straight sets to Fabio Fognini.
The Italian, seeded 13th, won 6-4 7-6 (8-6) in the third round - Nadal's worst result in Barcelona since 2003, when he was 16 years old.
It was Fognini's second straight win over the Spaniard, having won their Sao Paulo semi-final earlier this year.
"I played poorly, I didn't play like I should have," Nadal said.
"This is a blow for me, but I accept the challenge and the negative day I had. There is no other way forward other than to accept it or die.
"I will keep working. I am convinced that this situation of ups and downs I have had since returning from injuries, sooner or later, will come to an end."
Nadal, who has won the Barcelona Open eight times, has one title to his name since winning his 10th French Open last June.
|70||1st serve %||54|
|57||1st serve win %||70|
|52||2nd serve win %||50|
The 28-year-old, who began the European clay-court season with a run to the semi-finals in Monte Carlo, will take his preparations for Roland Garros on to the Madrid Open in two weeks' time.
Fognini, 27, grabbed a tight opening set with the only break in game 10 and would not let Nadal settle into his rhythm in the second.
The Spaniard was making an uncharacteristic amount of errors on his forehand and was pegged back three times after breaking serve.
"My forehand has been my biggest virtue," Nadal said. "But my forehand was vulgar, it wasn't a forehand worthy of my ranking and career."
Fognini levelled again at 5-5 thanks to a screaming forehand winner off a Nadal smash, and then forged into a 6-3 lead in the tie-break.
Nadal battled back to level at 6-6 but could not contain the errors when Fognini earned a fourth chance, and the Italian clinched a memorable win.
Top seed Kei Nishikori earlier beat Santiago Giraldo 6-2 6-1 in a repeat of last year's final, while third seed David Ferrer beat Swede Elias Ymer 6-3 6-4.