As has been the case for much of the tournament, Nadal was immaculate on serve. He offered up just a single break-point opportunity for Tsitsipas in the whole match, and that pressure told as the Greek youngster had to work hard to hold his own.
Tsitsipas did not play poorly, and he showed again he is arguably the most exciting young player in the men's game.
But he was outplayed by Nadal, who won in one hour, 46 minutes to set up a final clash with either Novak Djokovic or Lucas Pouille.
Tsitsipas never gave up against Nadal. He is a brilliantly talented player and proved on Thursday that he can be inventive in-game when he is trailing.
He attempted to disrupt Nadal by approaching the net more after the opening set. And it worked on occasion, most noticeably at 0-40 down in the fifth game of the second set when Tsitsipas held brilliantly, thanks in part to two excellent serve-and-volley points:
However, such was Nadal's consistency on serve that even when Tsitsipas held comfortably, he knew it would never be long until he was under pressure again with the ball in hand.
The Spaniard lost only 12 points on serve in the entire match, with three of them coming in the last game of the match when he momentarily lost a little concentration at 5-0 ahead.
Tsitsipas' only hope was to try to be similarly immaculate on his own serve, but Nadal did not allow that to happen:
The 17-time Grand Slam winner broke first for 2-1 in the opening set, with a pair of trademark thundering forehands giving his opponent little chance.
And Nadal then earned a double break for 5-2, this time taking advantage of two double-faults from Tsitsipas.
The No. 14 seed improved in the second set. As well as the excellent comeback at 2-2, he held three games comfortably, going toe-to-toe with Nadal up to 4-4.
But at the crucial moment, the 2009 Melbourne champion ratcheted up the pressure again to force two break points.
Tsitsipas tried the serve-and-volley tactic again, but this time it only worked once, and at 5-4 ahead, Nadal inevitably served out the set with a love hold.
The third set was one of brutal efficiency from Nadal as he demolished Tsitsipas, who made more errors as he tried ever more low-percentage shots in an attempt to turn the game around.
Nadal finally blinked as he served for the match, conceding a shock break point.
It was a momentary glitch, though, and he levelled for deuce before completing arguably the best performance of the tournament so far.