American Jessica Pegula beat a top-10 player for the first time in her career Monday, shocking fifth seed Elina Svitolina at the Australian Open to make her first ever Grand Slam quarter-final where she will take on compatriot Jennifer Brady.

Later, Czech 25th seed Karolina Muchova edged Belgium’s Elise Mertens in two tight sets to reach her second Grand Slam quarter-final while world No 1 Ashleigh Barty extended her unbeaten start to 2021.

Muchova was 0-4 down in the first before recovering to win 7-6 (7/5), 7-5 against Mertens, who beat Switzerland’s Belinda Bencic in the previous round. Barty was broken while serving for the match the first time but clinched it in the next game to get past Shelby Rogers 6-3, 6-4.

Unseeded 26-year-old Pegula has been in scintillating form at Melbourne Park and overwhelmed the Ukrainian 6-4, 3-6, 6-3 to set up a last-eight clash 22nd seed Brady who beat Donna Vekic 6-1, 7-5. Brady had reached the semi-final of the US Open while this is her best run in Melbourne.

Barty’s defensive mastery flummoxed big-hitting Shelby Rogers as she stormed into the quarter-finals to heighten hopes of a first home winner in 43 years. Chris O’Neil was the last home champion in 1978. The 24-year-old reached the quarter-final of her home Slam for the third straight year.

Having been pushed to the brink by Rogers just last week in the Yarra Valley Classic quarter-finals, an aggressive Barty stepped up the intensity with strong serving and blunted the American’s groundstrokes with a slew of brilliant retrievals.

Barty, who has been carrying a niggle to her heavily strapped left thigh, moved smoothly and counter-attacked superbly to thwart Rogers’ aggressive approach with an early break as the American dropped her first set of the tournament.

It was much the same in the second set with Barty using canny slices to toy with 28-year-old Rogers, who was aiming for her third Grand Slam quarter-final. Barty let slip two match points on serve in the seventh game but calmly closed it out on her next service opportunity.

Australian expectations are rising for Barty, whose side of the draw has opened up with the early exits of defending champion Sofia Kenin, world number five Elina Svitolina and world number six Karolina Pliskova.

American Jennifer Brady is the next highest seed in Barty’s bracket at 22.

Ranked just 61 and playing only her second Australian Open, Pegula took out former world number one and 12th seed Victoria Azarenka in the opening round then dropped just four games in her next two matches.

Svitolina had won in straight-sets when the pair met at Abu Dhabi last month but it was Pegula who took the initiative Monday, creating three break points that were saved before a double fault on the fourth handed her a 4-3 lead. She held serve to consolidate her advantage and take the set after some punishing baselines battles.

They traded breaks early in the second set before Svitolina held then broke again for 3-1 as Pegula temporarily lost focus.

But Pegula, who missed most of 2017 with a hip injury that forced her to consider retirement, bounced back in the decider and secured a crucial break in the fourth game with a backhand volley winner.

A double fault allowed Svitolina back, but Pegula broke again for 5-3 and served out for her biggest win. It was a disappointing end to a major again for Svitolina, who has fallen to players ranked outside the top 25 in the past three Grand Slams.