Ashleigh Barty's US Open campaign is over, with Australia's biggest women's singles hope falling to former finalist Karolina Pliskova in the fourth round.
The eighth-seeded Czech showed her class in a 6-4, 6-4 victory over Barty despite being under pressure for much of the match.
Barty won just about everywhere but on the scoreboard, striking 29 winners to Pliskova's 16, out-acing the Czech six to four and offering up only two break points on serve.
Tellingly though, Barty was unable to capitalise on any of her eight break-point chances, while Pliskova converted both her only two — one in each set, in the one-hour and 24-minute triumph.
Despite her exit, Barty's breakout grand slam run ensures the 22-year-old a career-high ranking of number 15 next week.
But while Pliskova was too clutch in the big moments, Barty paid dearly for her misfiring forehand.
She dropped serve from 40-love up in the opening game of the match, wildly overhitting a forehand with an open court in offing while down a break point.
The errors continued to flow from her favoured wing as she dragged another forehand wide while having Pliskova down 15-40 in the eighth game.
With Barty unable to break back, Pliskova served out the first set to claim the upper hand.
Serving at 1-1 in the second set, Barty double-faulted to gift Pliskova a second break point, which the Czech converted with a vicious backhand crosscourt winner.
For all her pluck, there was no break back for Barty as the 2016 runner-up edged to within two wins of a second grand slam final appearance in New York.
Barty remains in the hunt for a maiden grand slam doubles crown with the four-times runner-up through to the third round with American partner Coco Vandeweghe.
Pliskova will now play Serena Williams in the quarter-final, after she survived a brief scare to beat Kaia Kanepi in a fluctuating match, eventually securing the win 6-0, 4-6, 6-3.
Williams was dominant in the first set, before an unexpected fight back from Kanepi took the match the distance.
From there, Serena put the foot down again, and later said restoring her fitness — something that has been a challenge since returning from giving birth — played a big part in the win.
"I think the thing I have improved the most is my fitness," Williams said.
"I think coming back from a baby is really hard, harder than I thought, so the most important thing for me to improve was being fit and being able to stay and play long matches. That one really stands out."
John Millman is now the last remaining Australian in the draw, with the Queenslander awaiting a huge fourth-round clash with Roger Federer.
Elsewhere, there were wins for Rafael Nadal, who beat Nikoloz Basilashvili 6-3, 6-3, 6-7 (6-8), 6-4, and Dominic Thiem, who swept Kevin Anderson aside in a 7-5, 6-2, 7-6 (6-2) victory.