After breaking his racket on the hard court in frustration at the end of the 6-3, 6-4, 4-6, 3-6, 6-3 loss, Shapovalov said he felt like Nadal got special treatment.
There were plenty of momentum-shifting moments on a hot Tuesday at Rod Laver Arena, including Nadal needing treatment for a stomach ailment after dominating the first 2½ sets.
Shapovalov, meanwhile, openly complained to chair umpire Carlos Bernardes during the quarterfinal match about Nadal getting longer breaks than players usually are entitled to, and taking too long between points.
"I respect everything that Rafa has done, and I think he's an unbelievable player. But, you know, there's got to be some boundaries, some rules set," Shapovalov said. "It's just so frustrating as a player. You feel like you're not just playing against the player; you're playing against the umpires, you're playing against so much more."
None of it changed the fact that Nadal is one step closer in his bid for a men's-record 21st Grand Slam singles title.
The 35-year-old Spaniard shares the men's record of 20 major singles titles with Roger Federer and Novak Djokovic. Neither of those two are in Melbourne: Federer continues to recover from knee surgery, and nine-time champion Djokovic was deported for failing to meet Australia's COVID-19 vaccination requirements.
At a tournament where he has clinched the title only once (2009) and lost seven of his previous 13 quarterfinals -- by far his worst conversion rate at any of the four major tournaments -- Nadal looked vulnerable in the third and fourth sets.
But following a seven-minute break -- when Nadal left the court and went to the locker room -- between the last point of the fourth set and his first serve in the fifth, he recovered sufficiently to save a break point with an ace, hold serve and then break Shapovalov for a 2-0 lead in the decider.
"I don't know, was a little bit of miracle,'' Nadal said of his revival. "I was destroyed honestly physically. But my serve worked well, and for me, every game that I was winning with my serve was a victory, no?''
He rejected any assertion that he gets any special treatment from umpires or referees, and added that Shapovalov was young and said he would get over it.
"I honestly feel sorry for him. I think he played a great match for a long time," Nadal said. "Of course is tough to accept to lose a match like this, especially after I was feeling destroyed and probably he felt that, and then I was able to manage to win.
"I wish him all the very best ... probably he will understand later on after he thinks the proper way that probably he was not right today.''
Nadal had several medical timeouts in the four-hour match, but Shapovalov was particularly upset over the amount of time that Nadal was allowed to serve and the break before the fifth set.
"I mean, it was a big break after the fourth set for this reason, and the momentum just goes away," Shapovalov said. "... Every other match that I have played, the pace has been so quick because the refs have been on the clock after every single point. This one, I mean, after the first two sets it was like an hour and a half just because he's dragged out so much after every single point.
"He's given so much time in between sets and all this. It's just dragged out."
Shapovalov added later: "It's definitely emotional, but I do stand by my side. I think it's unfair, you know, how much Rafa is getting away with."
Nadal said he took "some extra time" at the end of the first and second sets to change his clothes, but he said that he does not get any extra treatment.
"I really believe that sometimes the -- it's always in the mind that the top players get bigger advantages, no, and honestly on court it's not true, no?" Nadal said. "That's my feeling. I never feel that I had advantages on court, and I really believe that he's wrong in that case."
Nadal held on to the break through the fifth set, and when it was over, he went to the corner and nodded his head a few times.
Shapovalov left a shattered racket on the court.
"I was completely destroyed. Tough day. Very warm," Nadal said. "At the beginning of the match I was playing great. Denis is very talented, very aggressive. He was serving huge -- especially the second serve.
"I think I had my chances at beginning of the third. I didn't get it. I started to feel a little bit more tired. For me, it's amazing to be in the semifinals."
Nadal will get two days off before Friday's semifinal match against seventh-seeded Matteo Berrettini. The Wimbledon runner-up, who became the first Italian man to reach the Australian Open semifinals, held on to beat No. 17 Gael Monfils 6-4, 6-4, 3-6, 3-6, 6-2.
"I'm not 21 anymore!" Nadal said. "After this ... great to have two days off. I felt quite good physically in terms of movement. At least it was a great test. I really believe I'm going to be ready for the semifinals."
The Associated Press contributed to this report.