Del Potro was leading 7–6 (3), 6–2 when Nadal retired with a right knee injury.
NEW YORK — Injuries have been Juan Martin del Potro's biggest nemesis throughout his tennis career. How ironic, then, that an injury to his opponent proved decisive in sending the big Argentine to his second Grand Slam final and first since 2009.
Del Potro was leading 7–6 (3), 6–2 in his U.S. Open semifinal over Rafael Nadal when Nadal retired with a right knee injury, meaning del Potro will have a chance to win his second career Grand Slam nine years after he won here as a 20-year-old.
He will face Novak Djokovic in Sunday's final.
"I can't believe I'll have another chance to play a Grand Slam final here," del Potro said. "It would be special to me, a big challenge as well, because I've been fighting with many, many problems to get back to this moment.
"But I'm here now."
Here indeed. Del Potro's ruthless groundstrokes and ability to turn defense into offense—made possible by his enormous wingspan, which allows him to comfortably reach balls others have to extend for—saw him take the front foot. Del Potro swatted 29 winner against just 17 unforced errors, while Nadal's only managed 15 winners against 15 unforced errors. That helped Del Potro win this match, which marked the fourth time in the last five Grand Slams that the two native Spanish speakers had faced off.
Nadal had won the three prior—a four-set tactical masterpiece in the semis here last year, a straight-set snoozer in the semis of this year's French Open and a five-set epic in the quarters of Wimbledon just two months ago—but his arduous slog through this draw certainly had a role in this outcome. Nadal spent 15 hours and 54 minutes across five matches to get to the semis, including a 4 hour, 49-minute marathon five-setter against Dominic Thiem in the quarters on Tuesday night.
Understandably never looking spry, the 17-time Grand Slam champion said he started feeling pain in the very early stages of the match.
"I think it was 2–2 in the first set, 15–love ... I said to my box immediately that I felt something in the knee. After that, I was just trying to see if in some moment the thing can improve during the match. But no, was not the day."
Del Potro was the fresher player from the onset, and the first signs of trouble for Nadal surfaced earlier than 2–2. Del Potro broke Nadal in the first game of the match and served for the first set at 5–4 before playing a tight game to squander that opportunity. In the first-set breaker, del Potro—or "Delpo," the nickname the not-too-numerous but delightfully boisterous Argentinian fans in attendance serenade him with—asserted himself with his massive forehand. The outcome was never really in doubt.
Del Potro couldn't capitalize on two break points in the second game of the second set, but by then it was clear Nadal wasn't at 100%. In Nadal's next service game, del Potro finally capitalized on his fifth break point of the second set to take a lead he wouldn't surrender.
Nadal called for a medical timeout and received a tape job from a trainer after the break, but his movement only worsened from that point on. After being broken for a second time that set to lose 2–6, he ripped off his headband upon getting to his chair and called it quits.
It's the first time a man has retired from a U.S. Open semifinal in the Open Era and the second time Nadal has retired in a Slam this year, having also stopped early in the Australian Open quarters while down 2-0 in the fifth set to Marin Cilic.
"This was not a tennis match at the end, no?" Nadal said. "It was just one player playing, the other one staying on the other side of the court."
Nadal emphasized that the pain was a familiar one that he thinks stems from tendinitis, which has given him issues throughout his career.
The win caps a remarkable comeback for del Potro, who has struggled with a true tennis kryptonite: wrist injuries. To both wrists.
In 2009, after he beat Nadal in the semi and Roger Federer in the final here to win his one and only Grand Slam title, del Potro looked to all the world like a multi-Slam winner who, along with Novak Djokovic, would challenge Nadal and Federer's theretofore joint stranglehold on the sport. He reached world No. 4 before missing most of the 2010 season with a right wrist injury, then battled back to world No. 4 again in 2014. That's when the other wrist wouldn't cooperate, and he would require two surgeries on the left wrist before returning for this later-career renaissance in February 2016.
Now 29 years old, the 6'7" man has reached a career-high world No. 3 is on the precipice of his second career Grand Slam at the same tournament that brought him his fondest tennis memories.
"Since I was a kid, I just watched soccer and the U.S. Open," del Potro said. "This is my favorite tournament."