Barcelona - Fourteen-time Grand Slam champion Rafael Nadal has described his performance as "awful" as he crashed out of the Barcelona Open 6-4, 7-6 (8/6) to Italian Fabio Fognini on Thursday.
Despite losing to world number one Novak Djokovic in the semi-finals of the Monte Carlo Masters last week, Nadal came to the Catalan capital in high spirits after playing the best tennis of his season to date.
However, the eight-time champion was stunned for the second consecutive year in Barcelona as Fognini edged a tight first set before fighting back from a break down three times in the second to seal victory in a tie-break.
"My play was awful and I didn't deserve to win," said Nadal.
"Fognini played better than me and deserved to win. Until I resolve the ups and downs I have had too often this season I will continue to be vulnerable.
"I made more mistakes than normal and didn't manage to maintain the advantage that I had in certain moments. To have a break three times in the second set and end up a 5-5 is a disaster."
Nadal sat out almost the entire second-half of last season due to injury and illness and has struggled to recover his form since the turn of the year.
The Spaniard has just one title to his name this season in Buenos Aires and his only victory over a top-10 player through seven tournaments came against David Ferrer in Monte Carlo.
The nine-time French Open champion was also beaten on clay in Rio de Janeiro by Fognini earlier this year.
Nadal has always managed to peak for the climax of the clay season at Roland Garros in Paris where he has only lost once and where he will target a 10th title next month.
However, he acknowledged that he has plenty of work to do at the Madrid and Rome Masters in the coming weeks to get in any sort of shape to hold off the challenge of Djokovic who is aiming to complete the career Grand Slam in Paris.
"A week ago in Monte Carlo I had a lot of good moments. It was the best so far this year, but this is completely the opposite, it has been a very negative week," added Nadal.
"I thought that I would be able to play more consistently, but it wasn't to be.
"I can only say goodbye to this tournament, one of the best ATP 500s and without doubt one of the best clubs in the world, and continue working hard to recover my best tennis."
Collated results on the fourth day of the Barcelona Open on Thursday (x denotes seeding):
Fabio Fognini (ITA x13) bt Rafael Nadal (ESP x2) 6-4, 7-6 (8/6)
Kei Nishikori (JPN x1) bt Santiago Giraldo (COL x15) 6-2, 6-1
Roberto Bautista Agut (ESP x7) bt Pablo Cuevas (URU x10) 7-6 (7/5), 6-2
David Ferrer (ESP x3) bt Elias Ymer (SWE) 6-3, 6-4
Martin Klizan (SVK x14) bt Victor Estrella Burgos (DOM) 6-4, 6-3
Pablo Andujar (ESP) bt Feliciano Lopez (ESP x5) 6-3, 6-4
Philipp Kohlschreiber (GER x12) bt Benoit Paire (FRA) 6-4, 7-6 (8/6)
Tommy Robredo (ESP x9) bt Marcel Granollers (ESP) 6-2, 6-2