The combination of heavy strapping on his left knee and anti-inflammatories - "magic pills", Del Potro called them - saw the Argentinian through a remarkably one-sided Centre Court quarter-final against world number four David Ferrer.
After falling and ricking the knee in the final stages of his third-round win over Slovenian Grega Zemlja, eighth seed Del Potro went over in an almost identical fashion today, inside the first game, as he chased down a ball to his left.
He lay on the ground, wincing in pain and clutching the knee before help arrived, first in the form of the trainer and then with the tournament doctor.
Somehow Del Potro recovered to pull off a 6-2 6-4 7-6 (7/5) victory, unleashing a barrage of just about the fiercest forehands ever witnessed at Wimbledon.
But he admitted he was "really close" to having to pull out of the match.
And while he would love to add a second grand slam title to his 2009 US Open triumph, the 24-year-old said: "I'm not going to put my body at risk. The doctors tell me that with this tape and some anti-inflammatories I can play. If they say something different, I will think.
"I think I was close to retiring. But to be honest, I didn't want to retire in my first quarter at Wimbledon against David Ferrer. The doctors gave me good anti-inflammatories.
"I was thinking good things, being positive all the time. I never thought about my knee after the first set."
Novak Djokovic, the world number one, title favourite and former champion, represents the high wall that stands between Del Potro and the final.
At 6ft 6in, Del Potro can almost peer over and imagine how it would feel to walk out for Sunday's showpiece.
And even if the knee does begin to affect him in the semi-final against Djokovic, Del Potro is certain his opponent will also be feeling the strain of two weeks on grass.
"I have experience with injuries. I know it's the semi-finals of a grand slam. All the players feel something, some pains. It's normal," Del Potro said.
"I have my knee problem, but my opponent could have different injuries. You have to be stronger than the rest."
In front of a Royal Box seating former champions Rod Laver, Jan Kodes, Richard Krajicek and Manuel Santana, Del Potro showed he can gun down shots big enough to knock Djokovic out of his stride.
He beat the Serbian to take Olympic bronze at Wimbledon last August, so anything is possible when they play on Friday.
"I will need to be 100 per cent or 110 per cent against him," Del Potro said. "He's the number one. He's a former champion here. It's going to be a more difficult match for me than today.
"But if I'm okay, if I do everything good to be ready for my next match, it will be exciting to play against him. I remember the match during the Olympics last year on the same surface.
"This time the pressure is different, but I will try to be ready and do my best."
Spaniard Ferrer had no complaints over the result, and dismissed the theory that Del Potro's early fall might have somehow altered the course of the match.
"I don't think it affected it," Ferrer said. "He fell over but I won the first game from break point down. I think Del Potro played better than me and deserved to win today."
Ferrer was carrying an ankle injury, but added: "It's no excuse. In the match it was perfect."