The world No. 1 and defending champion Rafael Nadal, limited by a right knee injury, has withdrawn from his semifinal of the US Open against the third seeded Juan Martin del Potro with the Argentine leader 7-6 (7-3), 6-2. .

He went to Del Potro's chair after the second set and shook hands. The players kissed and Nadal came out of great encouragement.

"Of course, this is not the best way to win a game," said Del Potro, the 2009 US Open champion. "I like playing against Rafa because he's the most great fighter. Do not like to see him suffer like he was today. In any case, the key to the match was the first set and we both played tennis well.

"I'm so happy to be in the final again."

This is the third time Nadal has retired in a Grand Slam match and the second this year.

He retired this year in the quarterfinals of the Australian Open, in the fifth set against Marin Cilic. He also retired against Andy Murray in the quarterfinals of the Australian Open in 2010.

Nadal, who has won the US Open three times, looked good early in the game, but the coach was on the field after the seventh game in the first set to complete the knee. A few parts later, he removed the bandage, but then asked the trainer to repack it in the second set.

It's been nine years since Del Potro won his only Grand Slam title. Shortly after, he began to suffer multiple wrist injuries, which has wreaked havoc in his career.

"I was a kid, but now I am a lot older," said Potro to the crowd to win here in 2009. "I hope to have one more day."

Nadal was able to save two points of separation with Del Potro, who served for the first set at 5-4, but helped the Argentine by amassing a setback on a third point at 6-3 in the break-up. 'equality.

Del Potro will face the winner of the semifinal between Novak Djokovic, sixth seed, and Kei Nishikori, 21st seeded.

Nadal, a 17-time Grand Slam champion who also won at Flushing Meadows in 2010 and 2013, seemed to suffer and stopped the rest of the second run after tightening his knee again.

Subsequently, he said the knee did not bother him on Thursday or earlier on Friday.

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Nadal, a battered clay master, had already played nearly 16 hours on the court before starting against Del Potro on Friday. His epic five-quarter match against Dominic Thiem on Wednesday would have been too difficult.

The match was held after 2 o'clock in the morning.

Contributor: Heather Tucker