Nadal defeated fifth seed Juan Martin Del Potro 6-4 6-1 6-2 in the semi-finals and afterwards the Argentine said it is "almost impossible" to beat Nadal on clay.
Seventh seed Thiem is in his first ever Grand Slam final in the latest high of a fine 2018 season which has seen him win titles in Argentina and Lyon and reach the final in Madrid - where he lost to Alexander Zverev.
2-nd player after Australia's Margaret Court to win a single Grand Slam title 11 times.
The victory also allowed the 32-year-old Spaniard to hold onto the No. 1 ranking.
- Nadal breaks to love to clinch the opening set as Thiem undoes all of his earlier hard work with a third forehand unforced error of the game into the net. Thiem broke the Spaniard's serve in the third game of the match, nullifying Nadal's early break but earned only one more break point - which was saved by Nadal. Well done, I'm sure you will win here in the next few years'.
He followed that up with his second title at Wimbledon with a straight-sets victory over Czech Tomas Berdych.
GETTYSerial winner Rafael Nadal is chasing a 17th Grand Slam title
After Roland Garros, Nadal's win-loss record on clay stands at 415-36.
He displayed his lethal weapon of single-handed backhand, while being troubled by unfavorable performance on his first serves, conceding the first set 6-4.
Rafael Nadal celebrates with the trophy after winning the French Open. So there was mild concern when Nadal called for the trainer midway through a game, requiring treatment on what looked like cramp in his hand.
Thiem is playing at his limit just to stay in touch.
Thiem was considered the stiffest test for Nadal at the French Open and understandably so. He's won a record-setting 10 titles on the clay at Roland Garros and often finished off his final opponents in straight sets.
"I mean, it's a big goal for me to play, soon, another Slam final", Thiem said. Nadal's streak began at Roland Garros past year and was ended by Thiem, who beat the Spaniard in straight sets in the quarterfinals of the Madrid Open. There is a slight chance of rain, but not until later in the afternoon after 5pm.