The already unpredictable 2014 men's tennis season was thrown for another loop Sunday when Rafael Nadal won a clay-court tournament that cast more doubt on his chances of winning the French Open that starts in two weeks.

Rafael Nadal loses in Barcelona for second clay loss of the season

According to The Guardian, Kei Nishikori was on the verge of handing Nadal his third clay-court defeat of the season - which would have been the first time in 10 years that Nadal had lost three matches on clay in a single season - when Nishikori suffered a back injury and had to withdraw.

The Japanese player took the first set 6-2 from the world's top-ranked player and was up a break and serving at 4-3 when the injury occurred. Nadal sent a ball beyond the reach of Nishikori's backhand; as Nishikori turned to try to hit the ball, he suffered a back injury that sent him to the ground, writhing in pain.

Nishikori had battled through the same injury in the semifinal against David Ferrer to get to the final. But Nishikori could not shake off the latest injury, losing the next three games to give Nadal the second set, 6-4.

Nadal then took a 3-0 lead in the third set before Nishikori retired.

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"We don't deserve the victory, (Nishikori) deserves it, he played better than us the whole time," Nadal's uncle and coach Toni Nadal told Antenna 3 TV, as reported by tennis.com. "We had a lot of luck today. We didn't really come back, he was hurt."

Toni Nadal added that Rafa reverted to the tentative play that cost him matches at Monte Carlo and Barcelona after Nishikori broke him twice in the first set in Madrid.

"I'm very sorry for what's happened," Nishikori told the Madrid crowd, The Guardian reported. "This is my first final and I was very excited. Unfortunately I was hurting already and trying to fight, but Rafa was too good. It was my hip, actually everywhere. My leg was hurting too."

The Guardian added that Nadal was "sheepish" in his comments to Nishikori during his post-match speech to the crowd.

"Kei, I hope you recover and I wish you all the best for the rest of the season."

Nadal, however, is probably wishing for all his own best to return for the rest of the season.

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