"In some ways he deserves victory too", a gasping Nadal said after setting up a blockbuster semi-final with Novak Djokovic.
That mishap could not stop Nadal from reaching his sixth Wimbledon semi-final and he celebrated the moment by raising both arms up into the skies after four hours and 48 minutes of thrilling action.
But Nadal was first to break in the deciding set and he built a 5-3 advantage with a looped forehand victor before confirming his final four place with a volley after four hours and 48 minutes.
Nadal has 17 while Djokovic has stalled on 12 since completing the career Grand Slam at Roland Garros in 2016.
Nadal worked the angles and moved superbly from the start, but the heavy-hitting Del Potro frustrated him by saving the first two break-point opportunities of the match before holding to level at 4-4.More news: No surprise Sterling is Croatian focal point, says Southgate
Del Potro was straining to stay in touch in almost every point, and his gambling instincts drove him to explore the white lines.
Del Potro, who'd saved four set points, grabbed one of his own on Nadal's serve and levelled at a set apiece with a forehand that clipped the net and fell inside the service box.
The deciding fifth set was a tight battle, but in the fifth game, Nadal got the solitary break to lead 3-2. There were no service breaks until the tenth game where Del Porto beat Nadal with a forehand victor to get the service break and set, 6-4. Del Potro made him pay as he pounced on his first chance to raise the prospect of another upset on day nine. Eventually, things went to a tiebreak Del Potro won to capture the set.
In the next game, Nadal staved off two break points, the first when he used his never-give-up-on-a-ball defense to stretch a point and del Potro pushed a forehand way long.
One such chase left Nadal toppling into the arms of a stunned woman sitting in the front row as he failed to put on the breaks as he dashed after a Del Potro smash.
Nadal saved a break point at 2-2, then took the lead courtesy of a strong backhand.