That win, according to three-times former champion Mats Wilander, should be all Thiem is thinking about when he prepares for Sunday's clash.
It is worth relaying, though, that in last year's semifinal, Nadal dropped just seven games total against the Austrian.
Del Potro would recover to win the match, 7-6 (5), 5-7, 6-3, 7-5.
The Argentine won the first two points to round off the first set and outlasted his Croatian opposite in lengthy rallies to win in three hours and 50 minutes. He needed two days to get it done after rain suspended play on Thursday when they were locked in the first-set tiebreaker.
Del Potro, playing in the semi finals here for the first time since losing to Roger Federer in 2009, was 0-40 ahead on Nadal's serve at 1-1 but could not press home the break and worryingly appeared to hurt his hip at deuce in that game.
The winners of the men's and women's singles finals this weekend will both take home a tournament record €2.2m (£1.9m/$3.1m) for triumphing on the clay at Roland Garros.
The Serb has a deal of work to do to get back to the stratospheric levels he reached before his right elbow gave up on him so spectacularly past year.
Despite some spirited resistance, the 11th seed couldn't live with Nadal's new-found intensity and revamped strategy, and the 16-time grand slam champion sealed the victory for the loss of only four games with his fourth match point.
And he will fancy his chances, having been the second best clay-court player in the world for the last two seasons behind Nadal, whom he has beaten three times, most recently in the Madrid Open quarter-finals last month.
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Tseng Chun-hsin of Taiwan has won the boys' title at the French Open by defeating top-seeded Sebastian Baez of Brazil 7-6 (7/5), 6-2.
"I have a plan", he said without elaborating.
"The second-set tiebreak was the big key to the match, 100 percent, because obviously he felt all the matches from these two weeks after that".
In the first semifinal, Dominic Thiem ended Cecchinato's Cinderella run via a 7-5, 7-6 (10), 6-1 victory. The French Open, like all Grand Slam tournaments, is best-of-five for men.
"But I will have to fight, and I'll do my best". But I get closer to them, just asking who was it? I think, and I didn't put not one bad face.
And yet, insists Nadal: "I just go on court knowing that every match is hard, and I can lose and I can win". "I think he showed that at the start of the match Rafa was very nervous and you have to keep his head under the water, and that's what DelPo couldn't do today", said Mouratoglou.
"When (Thiem) is dominating the point, he is very risky". "The good thing is, I played a lot of good matches this clay court season so Sunday is the day to give my best, it's a day to increase a little bit more the level".