However, the 32-year-old, who has won 16 Grand Slam titles, including 10 on the famous red clay, showed no signs of weakness when play resumed on Court Philippe Chatrier as he grabbed 12 of the first 13 points to lead by a break after he capped the second set.
"I'm really happy I won this match, it was very important for my mind to know I can beat a great opponent", said the 26-year-old Romanian. For me it's incredible.
"I know how to play against him", he said, without elaborating.
'My feeling is on Sunday I have a very hard match against a player that is playing great, ' Nadal said after beating Del Potro.
"I can not believe it now", Karin Thiem, a tennis coach, told a group of reporters. Basically, it's typical Nadal in the French Open.
A tired Del Potro looked like he could not take any more punishment when a Nadal backhand victor gave him a break to love in the first game of the third set.
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From the beginning of the match, the 10th-ranked Stephens was clearly superior on her serve, and offered resistance on Halep's. I'm really happy that it's happened at Roland Garros in Paris . "I said there is a chance to come back and win it".
"And I have to have a clear plan at the time of coming out on the court".
Expect him to do the same against the burgeoning talent of Thiem.
Sunday's showdown may represent Thiem's best chance of winning a grand slam so far, but the Austrian has attempted to downplay the situation by living up to his underdog tag.
Nadal emerged victorious in straight sets, including a memorable second in which he dropped just the one game.
"He's too strong", Del Potro said.
"Just thinking in a positive way and just thinking that I have to hold".
He suffered a worrying power cut in the second set, slipping to 5-0 down on a double break, wasting his seventh break point out of seven on the way. "I couldn't make it", said Del Potro. His last few seasons have been marked by inconsistency and injury, and Diego Schwartzman demonstrated that there are weaknesses to be exploited in Nadal's game.
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However, the banks declined to participate out of fear that doing so would harm their reputations. USA sanctions block Iran from exchanging the money on its own.
Trying to beat Nadal at Roland Garros in a best-of-five match is akin to trying to beat '08 Phelps in the individual medley, or 2012 Usain Bolt in the 200-meter dash.you get the picture.
"He's been a very complex opponent. He's a player that can be adapted more to the clay, it will be tough".
Nevertheless, Cecchinato can look back on a breakthrough tournament - he had never won a match at a grand slam before beating Marius Copil 10-8 in the fifth set last week.
Cecchinato's career has been tainted by his involvement in a match-fixing scandal; he was banned for 18 months in 2016 before having the suspension overturned. Both played superbly - and both had chances to end it. Thiem went ahead 6-3, but wasted three set points there, including a bad volley into the net at 6-4 that left him chewing ruefully on his left index finger.
"Not a very nice feeling", Thiem said.
While Nadal was untouchable previous year, he's been pushed to tiebreakers by Simone Bolelli and Maximilian Marterer.
6-1 defeat of surprise semi-finalist Marco Cecchinato ended that miserable streak, and Thiem, who has already beaten Nadal on clay this season, could now face the defending champion in the tournament decider. Then Thiem got to 10-all with a drop shot of his own.
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To prove the point, Sterling hasn't scored in his last 20 games for England , stretching back to 2015. England beat Costa Rica 2-0 at Elland Road in the Three Lions' final warm-up game for the World Cup .
Thiem sent Cecchinato scurrying around the court before breaking decisively for a 6-5 lead with a lovely forehand victor.