Emma Navarro [Source: Reuters]

Iga Swiatek booked her second Australian Open semi-final with another spectacular display on Wednesday while Americans reached the last four of the men’s and women’s singles at Melbourne Park for the first time in 16 years.

Defending champion Jannik Sinner was also at his impressive best as he dismantled local favourite Alex de Minaur 6-3 6-2 6-1 for his 10th victory over the eighth seed in as many matches and returned to the last four at Melbourne Park.

Polish world number two Swiatek mowed down eighth seed Emma Navarro 6-1 6-2 at Rod Laver Arena and faces another American in Madison Keys, who overhauled Elina Svitolina 3-6 6-3 6-4.

Ben Shelton wore down Italian Lorenzo Sonego 6-4 7-5 4-6 7-6(4) in a highlight-laden clash and ensured the United States has players in the men’s and women’s semi-finals for the first time since Andy Roddick and Serena Williams in 2009.

Searching for her first Grand Slam title, Keys will be hard-pressed to go further than Swiatek, who has crushed all five of her opponents at this tournament and is the only woman in the semi-finals to avoid dropping a set.

A throbbing ball of energy from the first point to the last, the five-times Grand Slam champion broke Navarro to love in the first game and was not prepared to concede a point – even when good sportsmanship might have warranted it.

In the fifth game of the second set and under pressure on serve, Swiatek bolted forward to retrieve a drop that bounced twice before her racket scooped it up.

Play went on, though, with Swiatek winning both the point and the game with a passing shot, leaving Navarro to remonstrate fruitlessly with the chair umpire.

Having not stopped the rally to dispute the non-call, Navarro had no recourse to challenge it – and Swiatek was not about to give the U.S. Open semi-finalist a break.

Most eyes have been focused on the top half of the women’s draw, where title favourite and double defending champion Aryna Sabalenka booked a semi-final with Paula Badosa on Tuesday.

But it may be the free-swinging Swiatek in pole position for the title, having lost only 14 games in her five matches.