Rafa Nadal ended a sub-par grand slam season on a heartbreaking note when he fell 3-6 4-6 6-4 6-3 6-4 in the third round of the U.S. Open to an inspired Fabio Fognini after winning the first two sets on Friday.

Clay court specialist Fognini, who was 0-7 on hard courts coming into the U.S. Open, played magnificently from the third set on, picking Nadal apart with groundstroke angles and deft play at the net, where the Italian won 39 of 54 advances.

The final set produced spectacular rallies and winners that had the Arthur Ashe Stadium crowd on their feet up to the 1:26 AM finish as the combatants traded seven service breaks in a row from the third game of the fifth set before Fognini held to end the three hour 46-minute tilt.

"Something incredible that I did today," said the 32nd-ranked Fognini, who won two out of three clay court matches against Nadal this year. "A very special win."

The loss ended eighth-seeded Nadal's record streak of 10 years in a row with at least one grand slam singles title after the Spaniard fell in the quarters at the Australian and French Opens, and was ousted in the second round at Wimbledon.

It was Nadal's first grand slam loss after winning the first two sets of a match. The only previous such defeat in his career came 10 years ago in the Miami finals to Roger Federer.

"He played great," said 14-times grand slam winner Nadal. "I'm not happy he played better than me, but that's what happened."

Nadal, 29, played his best tennis of the tournament in the first two sets and looked poised to register a straight sets win after breaking the Italian in the third game and taking a 3-1 lead.

But Fognini, 28, broke back in the sixth game and again in the 10th to extend the match.

Fognini, ripping outrageous winners from unexpected angles against the frustrated Spaniard, was down an early break again in the fourth set but broke Nadal in the fourth and eighth games to force a fifth set.

Like two fighters summoning all their energy for a late round knockout, they pounded away at each other, producing an electric finish that enthralled the crowd.

Fognini finished with 70 winners to 30 for Nadal, but the go-for-broke Italian also registered 57 unforced errors, more than triple of Nadal's 18.

The titanic struggle ended with Fognini having won 154 points to 152 for Nadal.

Fognini advanced to a fourth-round match against Spain's Feliciano Lopez, a 6-2 7-6 6-3 upset winner against 10th seeded Milos Raonic of Canada.