A rampaging Iga Swiatek stormed into her second Australian Open semi-final with a 6-1 6-2 centre court demolition of eighth seed Emma Navarro on Wednesday, while Madison Keys overhauled Elina Svitolina 3-6 6-3 6-4 in the earlier quarter-final.
The quarter-final passed with a note of controversy, though, with Swiatek scooping up a drop shot that looked perilously close to a double-bounce in the fifth game of the second set, which proved a hammer blow for Navarro.
Swiatek's win at a sundrenched Rod Laver Arena set up another American match-up with Madison Keys, with a 4-1 record in her favour.
After beating Ukrainian Svitolina, Keys had said she looked forward to cheering on Navarro as her compatriot took on the five-times Grand Slam champion.
But she was left to ponder the scale of her task as she looks to secure her first Grand Slam final since the 2017 US Open.
Most eyes had been focused on the top half of the women's draw, where 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 conceded only 14 games in her five matches.
Though the scoreline suggested otherwise, Navarro gave Swiatek a proper battle in the second set and had a break point in the fifth game tinged by controversy.
Swiatek bolted forward to retrieve a drop shot that appeared to have bounced twice on certain angles of the replay 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.
Navarro could not recover from the blow, losing the next three games to bow out.
While Swiatek squandered a first match point with a poor return into the net, she sealed it on the second when a desperate Navarro fired just wide of the line.
Madison Keys had earlier blasted into a third Australian Open semi-final with characteristic aggression to notch up her 10th win in succession.
The 29-year-old from Rock Island, Illinois had lost the last two of her three Grand Slam match-ups with Svitolina, most recently in the fourth round of the 2019 US Open.
And she appeared set for another setback as the counter-punching Ukrainian took full advantage of Keys' early waywardness on a cool and breezy morning.
Keys dropped serve in the eighth game with an unforced error and then gifted the set with another error as Gael Monfils nodded approval at his wife Svitolina from the player's box.
Keys raised her game, though, pressuring Svitolina on serve to earn a break point in the fourth game of the second set.
But Svitolina saved it with a brilliant reflex volley that left the American smiling ruefully.
Two games later, Svitolina finally buckled on serve as Keys found her range with a forehand winner. Keys had two set points at 5-3 but blew one with a wild forehand into the tramlines before closing it out with a big serve.
She kept up the firepower, raising two break points at 2-2 in the third set with a forehand down the line before taking Svitolina's serve with a ferocious backhand return.
Keys marched on in a barrage of power hitting, claiming the win on the first match point when a harried Svitolina thumped a backhand well past the baseline.