The 32-year-old Spaniard is 84-2 for his career at the French Open, winning four consecutive titles from 2005-08, another five consecutive from 2010-14, and No. 10 a year ago.
Nadal is hot favourite to win the second Grand Slam of the year after dominating on clay since making his Roland Garros debut in 2005.
The 10-time French Open champion was much more like his usual self, showing no signs of being troubled after having both wrists taped following the opening set in a lackluster performance the previous day. He repelled one match point on his own serve and pressured Nadal through two more at 5-2, earning three break points.
"It's tough to speak now", del Potro said.
"He was playing great, and I was playing too defensive". "I don't know if I will win, but I will take big love from you and that's most important for me".
"After the stop for rain I played more aggressively and I'm very happy to be back in the semi-finals here". "And in my opinion, the match changed", Nadal said.More news: Plastic pollution is a grave issue, stress experts
He was inconvenienced by a couple of break points as he served for the third set with 11th seed Schwarztman, a 5ft 7in live wire, refusing to go away quietly. The third operation, also in 2015, was a success, and since returning to the tour in March 2016, he has painstakingly worked on improving the strength in his left wrist, restoring his backhand from a one-handed slice back into the two-hander that was once as solid as his thunderous forehand.
In the other remaining quarterfinal, which will continue Thursday at Court Suzanne Lenglen, No. 3 Marin Cilic and No. 5 Juan Martin del Potro were at 5-all in a first-set tiebreaker when the play-ending shower came.
The pair were locked at 5-5 in a first-set tie break when the rain came, and it was fifth seed Del Potro who took the first two points upon the resumption to draw first blood. Additionally, emotion and momentum has to be on the side of Del Potro, who is thrilled to be at this stage, while Nadal faces all the pressure of expectations.
Del Potro, who lost to Roger Federer in the 2009 French Open semifinals, hit 31 winners against Cilic, including 19 aces.
Interestingly, Del Potro has never won a match on clay when priced in excess of [3.0], with his last outing ending in straight sets (and a final set bagel) at the hands of Andy Murray at this venue in 2017, so he will have to reverse this history, not to mention a 3-0 clay head-to-head deficit as well, to make Sunday's final. "I am doing well", he said after edging out third seed Cilic 7-6 (7/5), 5-7, 6-3, 7-5. "But now it's time to talk about my present in a good way. I don't have words to explain what this means to me and my team".