Coco Gauff beat sixth-seeded Petra Martic 5-7, 6-3, 6-4 to advance to the quarter-finals of the hard-court tournament at Memorial Drive.
Naomi Osaka, who won the US Open two years ago, advanced to the quarterfinals by beating No. 14 seed Anett Kontaveit 6-3, 6-4.
Palermo Ladies Open: Petra Martic to face Anett Kontaveit, Fiona Ferro against local favourite Camila Giorgi in semi-finals
Martic beat qualifier Aliaksandra Sasnovich 7-6 (5), 7-6 (3) then Kontaveit defeated Italian teenager Elisabetta Cocciaretto 6-1, 4-6, 6-1.
Petra Martić got past qualifier Liudmila Samsonova and will next face another qualifier, Aliaksandra Sasnovich.
Palermo Ladies Open: Kaja Juvan upsets Marketa Vondrousova in first round; Petra Martic beats Alison Van Uytvanck
Juvan was spoken to by the umpire after throwing items including her visor and wristbands to the crowd.
The WTA tournament, with qualifying beginning Saturday, marks the return of tour-level tennis following a five-month break for the coronavirus pandemic.
Auckland Open 2020: Eugenie Bouchard beats eighth seed Caroline Garcia; Alize Cornet fights back to eliminate Petra Martic
Bouchard, a former top-five player who made the Wimbledon final and semi-finals at the Australian Open and Roland Garros in 2014, has slumped to 262 in the rankings and is attempting to resurrect her career
Auckland Open 2020: Top-seeded Serena Williams eases past Camila Giorgi in American star's first match since US Open final
Playing her first singles match since losing last year’s US Open final to Bianca Andreescu, the 38-year-old Williams fired eight aces and was hardly troubled by Giorgi
Wuhan Open: Ashleigh Barty in party mood after epic win over Petra Martic, sets up Aryna Sabalenka re-match
Barty now gets a shot at revenge when she takes on powerful Belarusian Aryna Sabalenka on Friday in a rematch of their Wuhan semi-final last year.
The title was Karolina Pliskova's fourth of the season to add to trophies won in Brisbane, Rome and Eastbourne — moving her ahead of Australian world number one Ash Barty and Canadian Bianca Andreescu for most titles won so far this year.
US Open 2019: Serena Williams braves injury scare to advance to quarter-finals, China's Wang Qiang stuns World No 2 Ashleigh Barty
Eighth-seeded Williams, who has also suffered knee and back injuries this season, felt a mental setback when she took a tumble but battled through to win
US Open 2019: Serena Williams says her heart 'aches' on being away from daughter, equally committed to tennis and fashion label
Williams has been juggling her commitments towards playing tennis and managing her fashion label as also, raising her daughter Olympia
Serena Williams moved another step closer to a record-tying 24th career Grand Slam title with a comfortable victory over Karolina Muchova.
Wimbledon 2019, singles round-up: Coco Gauff's fairytale run comes to an end; Rafael Nadal reaches 39th career Slam quarterfinal
Coco Gauff’s dream Wimbledon run came to an abrupt end on Monday when the consistency of seventh seed and former world number one Simona Halep proved a step too far for the 15-year-old American, who went down 6-3 6-3.
Wimbledon 2019: Anastasia Potapova loses to Petra Martic on Court 16, but she’s likely to feature on Centre Court in future
You get the feeling Potapova feature on Centre Court in the future; she just needs to dial down her aggression long enough for her obvious talent to shine through.
Birmingham Classic: Ashleigh Barty remains in hunt for World No 1 ranking by setting up title clash with Julia Goerges
French Open champion Ashleigh Barty is one win away from becoming the first Australian to be crowned women's World No 1 in 43 years after reaching the final.
French Open 2019: Johanna Konta's impressive clay form makes her first Briton in 36 years to reach quarter-finals
Johanna Konta has barely put a foot wrong all week – and against the clay-happy Sloane Stephens, who was the 2018 finalist, the Briton looked firmly in control from the get-go.
French Open 2019: Roger Federer sets up Rafael Nadal clash in semi-finals; Marketa Vondrousova beats Petra Martic
Roger Federer finished off a 7-6 (4), 4-6, 7-6 (5), 6-4 win over friend and fellow Swiss player Stan Wawrinka to reach the French Open semi-finals
French Open 2019: Rafael Nadal sets up semi-final clash with Roger Federer; Jo Konta faces Marketa Vondrousova in last-four
Roger Federer set up a French Open semi-final clash with Rafael Nadal when he defeated Stan Wawrinka to become the oldest men's Grand Slam semi-finalist in 28 years.
French Open 2019: 19-year-old Marketa Vondrousova beats 31st seed Petra Martic to reach first Grand Slam semi-final
Marketa Vondrousova beat 31st seed Petra Martic 7-6 (1), 7-5 to become the first teenager into the semi-finals since 2017 champion Jelena Ostapenko.