A rain delay before the 11th seed could cement the break would turn the set on its head - and after a half-hour break, Nadal won three games in a row, only interrupted when the poor weather returned with the top seed two points from levelling the match.
Cecchinato, the world No 72 who bundled the former champion Novak Djokovic out of the tournament on Tuesday, gets his chance to go forward on Thursday, when he plays Dominic Thiem in the first semi-final.
The two remaining men's quarterfinals were suspended in progress and will resume Thursday.
Rafael Nadal was locked in an epic battle on Philippe-Chatrier before the rain ended play early on Wednesday night.
Nadal also called for a medical time-out at the end of the first set to receive some treatment on both of his wrists.
He may have halted the mutiny for now but Nadal was strangely off-colour, unable to dictate the rallies as he usually does on clay.
Manafort attempted to tamper with potential witnesses: U.S. special counsel
Court papers also accuse Person A of making several attempts to influence the witnesses' testimony in February and later in April. The alleged tampering with a potential witness, if true, would be a crime, violating the terms of Manafort's pre-trial release.
Qualcomm announces Snapdragon 850 for Windows PCs
Qualcomm has unveiled the Snapdragon 850 processor, which will power the next generation of always-connected Windows 10 devices. Qualcomm noted that Windows 10 devices powered by the 850 are expected to be available in retail before 2019.
Would you pay US$1,000 for a Trump-Kim summit medallion?
In addition, Kim has made two trips to China in recent months and met on Thursday with Russian Foreign Minister Sergey Lavrov. For Kim, recognition of his rule and nuclear power status of North Korea is the prime objective.
Breaks were swapped twice in the first set before 25-year-old Schwartzman broke the Nadal serve for a third time to lead 5-4.
More important than that, of course, is the match's ultimate outcome, and a significant moment came with Schwartzman serving while up 3-2 in the second after the initial delay.
Speaking on Eurosport's coverage of the Roland Garros, analyst Annabel Croft said Nadal had to overcome major stress to recover from being a set and break down.
Though Nadal hit back to level for 2-2, the plucky Argentinian broke again with a thumping forehand to regain control.
That was part of a 15-minute roll of three consecutive games for Nadal, a wave during which he collected 13 of 15 points to close in on that set.