1146 GMT October 14, 2019
The 32-year-old Spaniard cracked 29 winners in a 6-3, 6-4, 6-2 victory, BBC Sport reported.
The 17-time Grand Slam champion will play Stefanos Tsitsipas in the last four after the 20-year-old Greek beat Spain's Roberto Bautista Agut.
"It is emotional to be back in the semifinals," said Nadal, who retired injured in his quarterfinal against Marin Cilic last year.
"I had some troubles in this event so, after a while of not playing, to be back in the semifinal means a lot to me. I feel very lucky to be where I am after all the troubles I've been through."
Despite reaching at least the quarterfinals in 11 of his past 12 appearances, including four finals, Nadal has only converted one of these runs into victory – his sole triumph at Melbourne Park in 2009.
And, despite not playing competitively since September's US Open because of multiple injuries, he has cruised through his opening five matches.
The Spaniard used his trademark forehand to great effect, particularly down the line, hitting 13 winners on that side.
"The serve and winner with the first forehand is something very important for me, very important today, but also very important if I want to keep playing for a few years," he said.
"It has given me a lot of free points and that is so important at this stage of my career."
Tsitsipas, 20, followed his last-16 victory over defending champion Roger Federer with another four-set win on Tuesday.
Nadal has beaten the Greek in straight sets in both of their previous meetings – in ATP finals on clay in Barcelona and the Toronto hard-court last year.
"It is going to be a great year to be sharing generations, that's what makes this sport special – let's see what happens," Nadal said.
"During the last year he has been improving every month. He has already won a tournament and now in the semifinals and able to win against best players in the world.
"He is unbelievable today but he has the chance to be one of the best for a long time."
At 20 years and 168 days, Tsitsipas is the youngest man to reach the last four of a Grand Slam since Novak Djokovic at the 2007 US Open.
The Greek 14th seed won 7-5, 4-6, 6-4, 7-6 (7-2) in three hours and 15 minutes.
"It all feels like a fairytale almost. I'm just living the dream, living what I've been working for," he said.
"I feel a bit emotional but not too much because I know I really worked hard to get here."
Tsitsipas became the first Greek player to go beyond the fourth round of a Grand Slam when he knocked out six-time champion Federer to reach the quarterfinals.
He is the youngest man to reach the last four in Melbourne since Andy Roddick in 2003.
Any suggestion of a 'Federer hangover' was squashed by Tsitsipas, who demonstrated just why he is considered one of the hottest young prospects in tennis.
He said preparing for the quarterfinal was the "biggest challenge" he faced after "people went crazy" following the victory over his idol Federer.
"It was a great win and it got the people's attention but I had to stay concentrated and focused," he said. "I am happy that I played well today because it shows that it didn't happen accidentally.
"It doesn't feel real. My team asked me what my goals were this year and I said to reach the semifinals of a Grand Slam. I thought I was crazy answering this. But it is real and it just happened.
"I had a fantastic start in the tiebreak and I believe from my performance that I earned that tie-break. I am staying focused and aiming for more.
"I want to continue this amazing journey."