Only two players have managed to beat Nadal at the French Open since he first bounded into Roland Garros in 2005 armed with a bulging left bicep, pirate trousers and a pulverising brand of claycourt tennis the like of which had not been seen before.
Del Potro's play this tournament, plus his history against Nadal - the fifth seed won two of their three previous duels and was the last foe to down the Mallorcan in a grand slam semifinal in 2009 - suggested a close tilt.
The Spaniard will now face seventh seed Dominic Thiem of Croatia after he earlier defeated Marco Cecchinato of Italy 7-5, 7-6 (10), 6-1 in their men's singles semi-final match.
His 6-4 6-1 6-2 victory means he has now reached his 24th Grand Slam final and equals Roger Federer's record for most finals at a single major - Federer's coming at Wimbledon.
True, he was obliterated by Nadal in the semi-final 12 months ago but Thiem has added more aggression to his natural claycourt weapons, specifically the forehand, as he displayed when stunning Nadal in the Madrid quarter-final.
Rafael Nadal lifted the French Open trophy for an 11th time Sunday - and this time without the guidance of Uncle Toni.
The Sicilian journeyman usually earns a living by playing in second-tier tournaments, but over the past two weeks, the world number 72 looked like he belonged on the big stage.
Both players contributed to an entertaining start, but Thiem quickly took control, breaking through in the opening game and then comfortably holding easily. "I was 11 years old, watching in the TV and honestly never expected that one day I'd play the finals here".
Ominously for Thiem, Nadal said: "My feeling is I have a very hard match against a player that is playing great".
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The forecast says there is a chance of rain.
"I told him he needed to hit the ball very high and try to come inside the court".
Nadal has a 9-5 head-to-head record against del Potro.
Del Potro had required treatment on a hip problem suffered early in the first set and he visibly wilted in the second, raising his arms in mock celebration when he won a solitary game while already 5-0 behind.
The first set was a tight affair, with Thiem claiming the decisive break in the 11th game but the Italian retained his composure to send the second to a tie-break.
"I know I have to play my best, I have to improve a little bit".
"He's a big favorite against everybody", Thiem said. "When (Thiem) is dominating the point, he is very risky".
"Of course there is pressure especially in grand slam finals, because I went a very long way now and I don't want to lose the finals", he said. "Being in a final here is something I should rejoice about and be happy about", he said.
The 25-year-old was banned for match-fixing in 2016, a penalty overturned on appeal.
Increasingly frustrated at Cecchinato's resistance, Thiem lost his composure completely in the second set.
French Open headlines and quotes - Day 12
Brandon: After a shaky start, Nadal bounced back and put on a clinical display to dispatch of Schwartzman. Hard to believe now, but it wasn't long ago Juan Martin del Potro wanted to walk away from tennis.