Rafael Nadal improved to 11-0 in French Open semifinals.
In the second set, Schwartzman won the fifth game and led 3-2 when play was first halted.
The 32-year-old Spaniard, with 16 majors to his name, will play his 24th Grand Slam final at Roland Garros against Dominic Thiem who is in his first. After serving a fault, Nadal took the unusual step of heading to the sideline in the middle of a game.
On the resumption of play, Nadal held his two service points to take the second set 6-3.
Spanish tennis ace Rafael Nadal on Friday outclassed Argentina's Juan Martin del Potro to storm into his record 11th final of the French Open with a 6-4, 6-1, 6-2 win in the men's semi-final clash.
"The second-set tiebreak was the big key to the match, 100 per cent, because obviously he felt all the matches from these two weeks after that", the seventh seed said.
Nadal is now just the second man to reach 11 finals at the same Slam‚ equalling Roger Federer's mark at Wimbledon.
Del Potro insisted his hip had not troubled him during the match, instead putting the defeat down to one simple fact: "His game is too good for me".
But those are not quite the same as the French Open, where Nadal is 86-2 for his career.
The 10-time champion was much-improved under the sunshine on Court Philippe Chatrier after finding life hard the night before, clinching a 4-6, 6-3, 6-2, 6-2 victory over dogged Argentinian Schwartzman on his fourth match point. "I am doing well", he said after edging out third seed Cilic 7-6 (7/5), 5-7, 6-3, 7-5. However, Thiem did beat Nadal on the clay of Madrid last month.
Truth is, there were not many the rest of the way, as Nadal finished with 35 winners and just 19 unforced errors. Nadal claimed the final two points of that game in contrasting fashion, ripping a cross-court backhand that left the crowd gasping and deftly hitting a volley off a tricky net cord.
Nadal said: "Thiem is an wonderful player".
Thiem‚ who was playing in his third successive French Open semi-final‚ admitted the second set had been a nervy encounter after needing five set points to get through it.
What is definitely true: Thiem has never been to a Grand Slam final until now.
Thiem will be out of his comfort zone again when he goes into battle with Nadal in his maiden grand slam decider on Sunday.
What went through Nadal's mind right then?
A few hours earlier, as Nadal and Thiem warmed up, the booming voice of the announcer at Court Philippe Chatrier detailed the bona fides of both.
This was the No 5-seeded del Potro's first semifinal at Roland Garros since 2009.
And the underdog soon faded as Thiem kicked on, racing to two swift breaks in the third and rescuing two break points to serve out the match in style.
The 16th-seeded Gauff, who is 14 years old, beat 15th-seeded Leylah Annie Fernandez of Canada 6-4, 6-3.
The Argentine has never beaten Nadal on clay.
The forecast says there is a chance of rain.