Now only Dominic Thiem stands in the way of Nadal and what seems an inevitable 11th Roland Garros title.
The Spanish world No 1 edged a tight first set but then simply blew fifth seed Del Potro away.
It was swift and brutal. Del Potro had forced six break points during the first set but Nadal fended each one off.
Nadal, by contrast, had not had a sniff on Del Potro’s serve until, at 5-4, two swishes of his forehand forced two set points, the second of which he converted when the Argentinian netted.
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.
Relentless Nadal broke to love at the start of the third, and as he moved on to match point an exhausted Del Potro paused for breath, bent double, as if he had been punched in the stomach.
He probably felt as though he had been, as Nadal completed a devastating 6-4 6-1 6-2 victory.
His record at Roland Garros now stands at 85 wins and two defeats. One of those victories came against Thiem in last year’s semi-final and was, if anything, more comprehensive than this one. However, Thiem did beat Nadal on the clay of Madrid last month. Ominously, perhaps, for Thiem, Nadal said: “I have to improve a little bit.
“I believe I can be ready for that final. It’s going to be a tough one but I will fight all the way.”
Earlier Thiem needed to survive a nasty bout of the jitters to see off Marco Cecchinato and reach his first grand slam final. The Austrian was in control of his semi-final against the world No 72, holding three set points in a tie-break for a 2-0 lead.
However, having squandered one set point, he went in for a simple backhand volley winner only to dump it into the net.
The third quickly disappeared as well and Cecchinato had set points of his own, but Thiem finally put the Italian away before going on to win 7-5 7-6 (12/10) 6-1.
“I think the big key was the second set because it was a close tie-break,” said the 24-year-old.
“I saved two set points and luckily I won it.”