Mihaela Buzarnescu dumped Elina Svitolina out of the Birmingham Classic, while top seed Caroline Garcia was beaten at the Mallorca Open on Friday.
Svitolina was the highest ranked player in the quarter-final draw in Birmingham, with Garbine Muguruza knocked out earlier in the week, but she too fell by the wayside.
Buzarnescu defeated Svitolina at the French Open and she came out on top in a second meeting in a matter of weeks, triumphing 6-3 6-2.
"I didn't go on the court thinking I played her three weeks ago," Buzarnescu said. "She's an amazing player, so young and so many achievements until now and so many to come.
"I just tried to go on the court, play my own game and focus on each point and take it as an ordinary match."
Buzarnescu moves into her first WTA Premier-level semi-final, where she will face defending champion Petra Kvitova, who breezed past Julia Goerges 6-1 6-4.
Barbora Strycova and Magdalena Rybarikova make up the last-four draw, Lesia Tsurenko's retirement handing the former victory while Dalila Jakupovic lost to the latter.
In Mallorca, Garcia went down 6-3 6-3 to Sofia Kenin, with Lucie Safarova, another seed, also knocked out by Tatjana Maria.
Teenager Kenin will now play the first WTA Tour semi-final of her career.
"I'm very happy. [Garcia] is a great player," she said. "It was a really tough match and I knew I had to fight until the end."
Alison Riske was defeated by Sam Stosur, and third seed Anastasija Sevastova came from behind to get past Ajla Tomljanovic 3-6 6-3 6-1.
|Mbappe ready to take over from Messi and Ronaldo, says Trezeguet|
|Molinari: Ryder Cup pressure far outweighs any major|
|Koepka heads PGA Tour´s Player of the Year nominations|
|Lampard: Mourinho still a great manager|
|United States and Europe reveal Ryder Cup practice groupings|
|Bulldogs´ fine for ´Mad Monday´ antics halved|
|Bennett to leave Broncos after 2019 NRL campaign|
|American League postseason picture becomes clear|
|Steelers edge Buccaneers for first win|
|Gatland wants Webb available for World Cup|
|Modric: Ronaldo, Messi out of this world but my season deserved recognition|
|Love says Cavs ´will surprise a lot of people´|
|George believes Thunder can compete for championship this season|
|Messi is the greatest ever – Eto´o|
|Messi to miss Argentina´s upcoming friendlies|
|Dolphins say Hayes tore ACL attempting to avoid roughing-the-passer penalty|
|Modric deserved FIFA Best award – Ramos|
|Thibodeau open to potential Butler trade|
|Modric wanted Ronaldo, Messi at awards ceremony|
|Brewers´ Yelich active after elbow hit|
|Anthony on coming off Rockets´ bench: Whatever I have to do to help this team win|
|Raiders coach Gruden says Mack trade was hard on players|
|Bale lauds ´unbelievable´ Modric after FIFA Best triumph|
|Ronaldo, Messi lacked respect with FIFA Best awards snub - Capello|
|New Zealand the benchmark but England can win World Cup - Mitchell|
|FIFA Best Award a dream come true for Modric|
|Lakers a long way from Warriors, warns LeBron|
|Milner pokes fun at Salah´s Puskas Award win|
|Josh Rosen to replace Sam Bradford as Cardinals starting quarterback|
|Kaymer: Home-course advantage crucial to Europe hopes|
|Marta and Pedros win FIFA Best awards|
|I want to be in Toronto - Kawhi Leonard focused on Raptors, not future|
|Messi and Ronaldo lead FIFPro World XI as Salah and Neymar miss out|
|Knicks´ Kristaps Porzingis ´itchy´ to return but won´t commit to 2018-19 season|
|Modric beats Ronaldo and Salah to FIFA Best prize|
|49ers confirm ACL tear for QB Garoppolo|
|Salah beats Bale and Ronaldo to Puskas Award|
|Deschamps wins FIFA Best Men´s Coach award|
|Law to leave Windies for Middlesex role|
|Sunderland terminate Ndong´s contract|
|Spalletti warns rejuvenated Inter against complacency|
|Ryder Cup 2018: Figo in town as USA arrive in style|
|Browns name Baker Mayfield starting QB|
|Chelsea need to be more versatile, warns Giroud|
|Paris Saint-Germain FFP case referred by UEFA back to CFCB Investigatory Chamber|
|Busy Bertens ready for bed, Muguruza gains Wimbledon revenge|
|Hart ready if England come calling - Dyche|
|Ryder Cup 2018: An honour and a burden - the unique challenge of captaincy|
|Hibino beats Bouchard again at the Tashkent Open|
|Falcons lose Ricardo Allen for season|
|Mbappe three-match ban stands following appeal|
|Tomic wins first Tour-level match since Wimbledon in Chengdu|
|Ryder Cup diary: Scoreboard shocker, captains tight-lipped|
|Mourinho will spawn lots of managers - Lampard|
|Furyk outlines Woods´ Ryder Cup motivation|
|Tiger doesn´t scare Team Europe - Bjorn|
|Ryder Cup 2018: Team USA profile|
|Woods winning ´incredibly special for golf´, says Poulter|
|Grealish commits to Aston Villa with five-year deal|
|Ryder Cup 2018: Four reasons why Team USA will win|
|Herrera ready for return - Mourinho|
|Bellew determined to prove doubters wrong against Usyk|
|Lewandowski and Boateng´s professionalism impresses Kovac|
|WATCH: Sheepish Murray comically drops commemorative plate in China|
|Cech: Arsenal have forgotten how to win Premier League titles|
|Lemar must adapt to Atleti style, says Simeone|
|Toulon to appeal suspended points penalty|
|AFE rejects Miami plan for Girona-Barca|
|Messi and Ronaldo to decide world´s best young player|
|Ryder Cup 2018: Talisman Poulter key to European hopes|