It's been a year to forget for Rafael Nadal. The former No. 1-ranked player has endured his share of setbacks in 2015, and his latest loss might have been the most heartbreaking.

On Friday night at Arthur Ashe Stadium, Nadal fell to No. 32 Fabio Fognini 3-6 4-6 6-4 6-3 6-4 in the third round of the U.S. Open after looking like he had his typical form in winning the first two sets. It was a disappointing effort for the Spaniard, who often made uncharacteristically poor ground strokes despite showing his trademark athleticism with fine runs along the baseline. It was the earliest exit for the 14-time Grand Slam winner at Flushing Meadows since falling to American James Blake in 2005.

"The only thing this means is I played worse than the last 10 years," Nadal said. "That's the real thing. By the way, for me it was amazing to win 10 years in a row a Grand Slam.

"You can imagine how difficult it is to make that happen. I have to accept that it was not my year and keep fighting till the end of the season to finish in a positive way."

With a string of underwhelming performances, it's clear Nadal is not quite the player he once was. The 29-year-old came up short against Tomas Berdych in the quarterfinals of the Australian Open, and even at the French Open, his favored tournament and surface, lost to No. 1 Novak Djokovic in the quarterfinals. Wimbledon was his worst finish, losing in the second round of Wimbledon to Dustin Brown. While he showed flashes on Friday of the Nadal that won the U.S. Open twice, he simply looked overmatched in the later sets by a more spirited opponent.

Fognini, who entered the tournament with an 0-7 record on hard courts, also made his share of errors, including a missed overhead that he took from the middle of the court and went straight into the net. But he did enough to defeat the tennis legend with some excellent forehands up the line and powerful shots that had Nadal scurrying around the court. The aggressive Italian ended up finishing with 70 winners and 57 unforced errors, compared to 30 winners from Nadal, and 18 unforced errors.  

"I can't describe how happy I am," said Fognini. "It was very tough -- to do it against Rafa, two sets down - it was an incredible match."

Next up for the 28-year-old is a fourth-round matchup with Feliciano Lopez of Spain.