Nadal was back to needing one game to claim the set.
A set littered with one lengthy rally after another, eventually went to Nadal on serve, finally giving him the match.
Nadal saved three break points before an imperious forehand victor put him 5-3 up and he put away a simple volley to finally finish off Del Potro, then made his way around the net to embrace his tired opponent as he lay on the court following another tumble.
"The last set had a little bit of everything, great points, great rallies, he was hitting insane with his forehands". I tried to resist and maintain focus. "It's a day to be happy".
Del Potro let two break-back points slip in the sixth game and then forced Nadal to save three more breaks for 5-3.
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Even then he was left flat on his stomach as his racket went flying out of his hand.
"Rafa is a fighter".
"I was close to beating him and I couldn´t because Rafa always has a little bit more than the rest of the players on tour". "In some ways he deserves to win as well", said Nadal after the breath-taking quarter-final.
"I wanted to stay there", del Potro said afterward, "all night long".
A few hours earlier, however, it looked as if it was going to be 32-year-old Nadal who would end up down and out.
The fifth seed had led by two sets on Monday but Simon grabbed the third set before fading light ended play.
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It was not as if Nadal was playing badly.
It was as if that out-of-the-blue news threw the Spaniard off his stride and he fluffed his lines to drop his serve.
There was a look of glee in Del Potro's sometimes sad eyes, and his lumbering between-points walk had a bit more energy to it. Nadal, struggling to get a solid second serve into hard areas, was de-fanged for long stretches.
That blip was enough for Nadal, chasing an 18th Grand Slam title, to surrender his first set of the championships.
However, Del Potro was made to pay for a sloppy game when he was serving to secure a tiebreak, netting a backhand to go a set down.
A tired Del Potro, a semi-finalist in 2013, finished with 33 aces and 77 winners but even those impressive statistics were not enough. Only negative thing is I played nearly five hours, and I had the chance maybe to play less winning that second set.
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