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.
"I wanted to stay there", del Potro said afterward, "all night long".
In an odd-numbered year, the exit of Roger Federer in a five-set thriller, followed immediately by the triumph of Rafa Nadal in a five-set thriller on Centre Court, would have dominated the sports pages, but unfortunately for tennis fans, England had to go and get to and get beat to Croatia.
Nadal, in the quarter-finals for the first time since finishing runner-up to Novak Djokovic in 2011, carved out the crucial break in the opening set for a 6-5 lead and claimed the opener off a Del Potro backhand error.
"Rafa is a fighter and he has a fantastic game".
Victory secured, Nadal climbed over the net and ran over to the baseline to help the distraught Del Potro back to his feet.
The fourth-round match resumed on Tuesday afternoon after bad light had stopped play on Monday with the Argentinian leading by two sets to one.
The world number one had lost only nine points on serve when, just before the ninth game of the second set, the result of Federer's shock demise was flashed up on the giant on-court scoreboard.
Soon, Nadal gained the upper hand, shaking off a hard fall onto his back on one point by whipping a cross-court backhand victor on the next to break for a 3-2 lead.
Del Potro too noted the change in conditions but appeared to relish the chance to slide around a bit more on the grass.
Simon failed to convert a break point, then a third match point for Del Potro ended with him netting a forehand.
John Isner has reached his first Grand Slam semi-final on his 41st appearance.
"Anything could have happened, so this is a big achievement for me to get to the semi-finals at Wimbledon".
There was, however, one consolation for Del Potro who came off second best despite belting down 33 aces and producing 77 staggering winners, 10 more than Nadal.
"I play Los Cabos in Mexico - the beach", he smiled.