The 32-year-old world number one has won 10 French titles and has only been beaten twice in his career at the red clay grand slam tournament.
However, even though his dominance of the event makes him a heavy favourite, Nadal goes up against a youthful and big-serving Thiem, who will be competing in his first major final.
Nadal expects a varied performance from the 24-year-old Austrian but remains ready for whatever his young opponent throws at him.
“With the years, you learn that things change very quickly,” said Nadal when asked about the age gap factor ahead of his 24th slam final.
“You must never let opportunities go by. You must always think that things might get better or you have to be with your eyes open so that you don't lose your positive energy.
“I know I have to give a little more than I have given until now in this tournament. This extra thing I have to give, I feel I have it inside me, but I have to go and get it.
“Thiem is a very complex opponent. He's one of the best players in the world on this surface. I hope that I can win.”
Indeed, Thiem is the only man to beat Nadal on clay this year, having triumphed at the quarter-finals in Madrid masters event and also earned success in last year’s edition of the Italian Open in Rome.
However, those victories were in best-of-three-set contests and Thiem has never conquered Nadal in the major format, with his last attempt at the 2017 French Open final four ending in straight sets 6-3, 6-4, 6-0.
Thiem remains confident that history won’t repeat itself on Sunday, adding he will arrive on Court Philippe Chatrier with a clear mind.
“I have a plan,” he said. “I will try everything that my plan [is] also going to work out a little bit here and not only in Madrid or in Rome.
“He likes the conditions more here than in Madrid, for sure. Best of five is also different story. I think also it’s a good thing that I faced him already twice here.
“I think if I'm facing Rafa, I'm not the one who has the pressure.”