Then, at 4-3, they played an epic 18-point game that featured six deuces and another trio of break points for del Potro, none of which he managed to convert.
"I wanted to stay there", del Potro said afterward, "all night long".
Incidently, the Nadal versus Del Potro match lasted exactly the same length as Rafa's win against Roger Federer in the 2008 final.
Rafael Nadal will face Novak Djokovic in a mouthwatering Wimbledon semifinal after beating Juan Martin del Potro in a Centre Court classic Wednesday. It had a little of everything, great points, great rallies, he was hitting insane with his forehands.
"Rafa is a fighter and he has a fantastic game".
After two-and-a-half hours, Nadal and Del Potro were still a set-all and three-all.
Del Potro refused to surrender, breaking back in game 10 to level the score at 5-5 and he saved four set points in the tie break, climbing back from 3-6 down to steal the set 9-7 and make a huge roar of relief, ready to fight until the very last point.
Roger Federer vs Kevin Anderson, Wimbledon 2018
It will be the 31-year-old Serb's first semi-final at a Slam since the 2016 French Open when he completed the career Grand Slam . Kevin Anderson , left, rallied from two sets down to deny Roger Federer's bid to win his ninth Wimbledon title this year.
Del Potro threw everything he could at Nadal in a pulsating match and even conjured the shot of the tournament as he acrobatically dived to his right to hit a fizzing forehand volley that ended a spellbinding 23-shot rally.
Del Potro too noted the change in conditions but appeared to relish the chance to slide around a bit more on the grass.
But the second seed stayed alive by taking the fourth set before the gripping drama continued in an electrifying deciding set in which both players were left diving after volleys and slipping over as they sprinted after blinding winners.
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.
The second seed, eyeing a third Wimbledon title, with his last triumph at SW19 coming eight years ago, struck 66 winners compared to 77 from Del Potro, who fired down 33 aces in a contest that ebbed and flowed throughout.
"Anything could have happened, so this is a big achievement for me to get to the semi-finals at Wimbledon". Only negative thing is I played nearly five hours, and I had the chance maybe to play less winning that second set.