Del Potro lost almost two years, undergoing three operations and fearing his career was finished.
Djokovic said: "I personally like him very much, not just as a player but as a person". But no, was not the day.
Nadal received treatment on his knee at 4-3 in the opening set, which he lost to his Argentinean opponent in the tie-break. "[But] I was not feeling worst of my knee before the match or [Friday] when I practiced". He barely took any time between points while serving - and he's known as one of the slowest guys on tour.
"That was not a tennis match at the end". I like to play big battles with other guys. "I think the key to the match was the first set".
It was in 2015, the year of his fourth wrist operation, that Juan Martin del Potro was pretty sure he'd had enough.
Across the net, the slow-moving Del Potro, who has made the moniker "Gentle Giant" his own, refused to get distracted.
Perhaps it's because del Potro was sandbagging. "I'm sad for him".
The three-time champion retired at the end of the second set with Del Potro leading 7-6 (7-3) 6-2 on Arthur Ashe.
He had his right knee taped during a long third-round match against Karen Khachanov and had survived a brutally physical encounter with Dominic Thiem in the last eight. Tendonitis has dogged him.More news: Florence expected to become 'major hurricane' by Monday
"I'm very happy for my level, for what all I have been through to get in this position now", del Potro said. "This time it was a little bit more aggressive with my movement", said Nadal. Was not something progressive.
As everybody knows, this is my favorite tournament since I'm kid.
Six months later, tendinitis hit again and impacted on his participation at Roland Garros, where he suffered defeat to Robin Soderling. "It's where you want to play your best", Djokovic added. Del Potro knows how it feels to deal with injuries as he had four wrist surgeries.
He is 45-4 this season, with half the losses due to injury retirements. This year have been a fantastic year until this moment.
"I am playing the right way and enjoying things". I think it's important to feel in these conditions. Lot of people in this room, including myself, never will think that at the age of 32 I will be here fighting for titles, fighting for the first positions of the rankings.
Djokovic said: "Seeing the consistency of the results I've had here, probably it has been my most successful Grand Slam".
Novak Djokovic sat out last year's U.S. Open to rest an elbow injury that eventually required surgery, but that pain and frustration felt like a distant memory on Friday when the Serb completed his march to the NY final with authority. This is my favourite tournament, my biggest memories on a tennis court came on this court in 2009.