He quickly moved 3-0 ahead in the second set and, although Djokovic initially showed some fight, it soon drained away.
He said: "Trust me, I'm thinking about many things, especially in the last couple months".
"I'm grateful for the attention but there are many other players that deserve that as well". "I knew he was playing good, but I was confident with what I was doing since the beginning of the tournament".
"I know that I have achieved the biggest heights in this sport, and that memory and that experience gives me enough reason to believe that I can do it again, although I'm aware that I'm not the only one", he said.
Thiem said that while he feels relieved and excited to have beaten Djokovic, he knows he can not settle heading into his contest with Nadal. I have to get through it and learn the lessons and come back stronger.
Djokovic led 4-2 in what was a brutally physical first set lasting 73 minutes but played a poor game to hand Thiem the break back, serving two double faults.
The 29-year-old reached the semi-finals of last week's Madrid Open Masters before the finals loss at Rome.
Djokovic's backhand really let him down in the tiebreaker: All seven points won by Thiem ended with that stroke. On Friday (I play) Nadal.
"So far I have always played a way worse match the following day if I beat a top guy, so I hope I can improve that", Thiem told reporters.
Murray is in the semifinals in Paris for the fourth year in a row.
Facing a player he had destroyed in their previous meeting on clay last month, the former No. 1 Djokovic was routed 7-6 (5), 6-3, 6-0 by the 23-year-old Thiem.
Wawrinka, who lifted the Musketeers' Cup in 2015, ended Cilic's ordeal on his first match point with a second-serve ace.