Sinner demolishes De Minaur to set up Melbourne semi with Shelton
The Italian world number one showed no signs of the illness that hampered him in his last match to emphatically fly past the eighth seed 6-3, 6-2, 6-1 on Rod Laver Arena.
He will meet stubborn American Shelton for a place in Sunday's final against either 10-time champion Novak Djokovic or second seed Alexander Zverev.
Shelton, seeded 21, battled past another Italian, the unseeded Lorenzo Sonego, 6-4, 7-5, 4-6, 7-6 (7/4) to make the Melbourne Park last four for the first time.
The writing was on the wall for De Minaur with Sinner winning all nine of their previous meetings -- the Italian had also won all 20 of his last matches against Australians.
De Minaur was given a glimmer of hope after Sinner battled illness in his last-16 clash, where he admitted he was "not there health-wise" and had been "a bit dizzy at times" in hot weather.
But the Italian showed no evidence of the issues on a much cooler quarter-final day, moving freely and displaying no discomfort.
In front of a patriotic home crowd, he broke for a 3-1 lead after a draining 24-shot baseline rally.
The agile Sinner's big ball-striking proved hard for the Australian to counter and he struggled to create chances, managing just four winners in the opening set.
The second set followed a similar pattern with Sinner bossing De Minaur, pushing him around at will and breaking immediately to take control.
He was on a mission and a forehand winner earned him a second break on his way to the second set in 40 minutes, with the Australian shaking his head, wondering what to do.
De Minaur tried everything, but had no answers, broken twice in set three after a series of errors as Sinner powered 3-0 clear.
Sinner is bidding to defend a Grand Slam title for the first time after beating Daniil Medvedev in the final last year, and is also seeking to become the first Italian man to win three Grand Slam crowns.
He also won the US Open last year.
'Ridiculous tennis'
Shelton, a year younger at 22, will be awaiting him on Friday.
The American demonstrated his potential by reaching his first semi-final at the US Open in 2023, where he was beaten by eventual champion Djokovic.
The elastic left-hander came through a tough encounter with Sonego dominated by booming serves.
One monstrous ace sent down by Shelton clocked at 232kph (144mph), the joint-fastest serve of the tournament.
Shelton had the edge for the first two sets, but he suffered a mid-match wobble before rallying to come through a tense fourth-set tiebreak.
He said afterwards that he wasn't worried about who he played next.
"If it is the home favourite Alex de Minaur, then 100 percent, you can boo me, throw stuff at me. I understand," Shelton told the crowd after his win.
"If it is the world number one, probably the same thing, but I've got a few people in the crowd who will be pulling for me too.
"I feel so relieved right now," he added. "Shout out Lorenzo Sonego, that was some ridiculous tennis."