"You feel like every shot in Dominic's game has got some punch behind it", Federer said during his post-match press conference.
"The fricking champion of Indian Wells", Andreescu said.
'It feels not real at all, ' added Thiem, the first Austrian to win a masters 1000 title since Thomas Muster at Miami in 1997.
He cruised through the first set in 36 minutes while getting broken for just the second time during his run to his ninth appearance in the final.
"He stayed cool under pressure there", Federer said. Thiem served out the two-hour match that ended with yet another error from Federer, a forehand dumped into the net.
Nadal, whose longstanding right knee trouble flared up in his quarter-final victory over Karen Khachanov, couldn't take the court for the blockbuster semi-final with Swiss great Federer. He was beaten in a third-set tiebreaker by Juan Martin del Potro in 2018.
Thiem had more service winners and forged the advantage in both the shortest rallies up to four strokes and in those mid-range ones to cement the triumph and crack the top-4 for the first time in a career on Monday.
From thereon, it was too late for Federer to recover as Thiem claimed it 7-5.
Thiem really showed his might to save a break point and hold at 4-4, and did not allow a nasty fall and bloody elbow to set him back as he edged the 37-year-old three games later to serve for the title.More news: New Zealand gov't support strict gun law
"My goal is to play on all the surfaces", an emotional Nadal said.
Federer believes Nadal is playing better than he did in losing the Australian Open final to Novak Djokovic, who was upset earlier in the week.
Thiem earned the only break of the second set in the fourth game, going up 3-1.
Against Hurkacz, Federer fought off two break points in the second set, including the last game when he closed the match with a forehand victor off a short ball.
Nadal leads their rivalry 23-15, but Federer has won five straight, most recently in the final of the Shanghai Masters in 2017.
A similar story unfolded in the 2nd set with the world no.4 winning the decisive break in the 3rd game (2-1).
Federer explained the nature of his performance and how the milestone of winning his 100th ATP tour title in Dubai a few weeks ago took the sting out of this defeat. I had my chances.
"I hope he celebrates this moment tonight with his team", he said on the Amazon Prime broadcast.