Tsitsipas got an early break in the opening set, aided by two double faults from Zverev.
The 22-year-old remained solid against the German’s heavy ground strokes to hold onto his narrow advantage on a sun-bathed Court Philippe Chatrier.
US Open finalist Zverev built a 3-0 lead at the start of the second set but Tsitsipas showed exemplary athleticism and staunch defence to win the next six games, leaving the former staring at his coaching team bewildered.
The sixth-seeded German, however, regrouped and added more power to his shots, with early breaks in the third and fourth sets enough for him to level the match at two sets apiece.
Tsitsipas needed to change his game in the decider and managed to find an extra gear and seal the contest on his fifth match point.
“All I can think of is my roots, and where I came from. I came from a small place outside Athens. My dream was to play here, to play on the big stage of the French Open one day. I never thought I would do it,” said Tsitsipas after the semi-final victory.
“The opening game was the most important one in the fifth set. I came back, stayed alive and had the crowd with me. They gave me the energy. I felt that there were opportunities to fight back in the match and that is what I did,” added Tsitsipas.
Pavlyuchenkova, Krejcikova one step away from title
After one of the most wildly unpredictable women’s singles draws in French Open history, Russia’s Anastasia Pavlyuchenkova stands on the threshold of finally delivering the title.
It has been a protracted journey for the 29-year-old, who at the 52nd time of asking has reached her maiden Grand Slam final. She will take on unseeded Czech Barbora Krejcikova, who has also broken new ground this fortnight.
Trying to predict who will get their hands on the Suzanne Lenglen trophy is perhaps unwise at the end of a tournament in which seeds have withered in the Parisian sunshine.