Kristina Mladenovic ended the challenge of the teenage wildcard Hailey Baptiste in Washington with a 6-4 4-6 6-3 victory to reach the quarter-finals of the Citi Open.
The 17-year-old Baptiste had beaten the US Open finalist Madison Keys last time out and went down swinging as she lost her second-ever WTA main draw match.
Baptiste was ranked over 200 places below her opponent and Mladenovic made life difficult for herself before ultimately prevailing.
The Frenchwoman put down 11 double faults and saved seven of the nine break points that she faced during the two hour and five-minute match against Baptiste.
Mladenovic is into her fifth quarter-final of the season and will face Russian qualifier Anna Kalinskaya, who upset eighth seed Monica Puig 2-6 7-6 (7-5) 6-4.
Meanwhile, third seed Sofia Kenin saw her hopes in Washington squashed by Lauren Davis as the 25-year-old continued her form after dispatching Eugenie Bouchard 6-1 6-2 on Tuesday.
Davis lost the opening set against Kenin but the former finalist in Washington show her fortitude to beat the highest remaining seed in the women's draw by 5-7 6-3 6-4.
The reward for Davis' work will be a last-eight meeting with Jessica Pegula who came from a set and a break down to prevail over 18-year-old Iga Swiatek 5-7 6-4 6-1.
Thursday's order of play in Washington will see the other two quarter-final matches decided. On the Stadium Court there will be an all-American clash as Catherine McNally meets Christina McHale
Elsewhere Italy's Camila Giorgi takes on Rebecca Peterson, who beat Sloane Stephens in the opening round to claim her first top 10 scalp.
Zarina Diyas encounters Lesia Tsurenko and both players share a 2-2 record when it comes to their head-to-head meetings.
Finally, Hsieh Su-wei is taking on the qualifier Varvara Gracheva and could progress into her first WTA Tour quarter-final since May if she is victorious.
Away from Washington at the Silicon Valley Classic, the top seed Elina Svitolina opened her campaign with a straight-sets win over Daria Kasatkina.
The Ukrainian was given a bye in the first round and ultimately made quick work of her 6-3 6-1 victory over the Russian, spending just over an hour on court. Svitolina will now face Maria Sakkari as she continues her debut in San Jose.
Elsewhere, wildcard CoCo Vandeweghe lost to second seed Aryna Sabalenka 6-3 6-3, Carla Suarez Navarro defeated Bethanie Mattek-Sands 3-6 6-1 6-2.
As the draw unfolds for the remaining quarter-final places the pick of the bill sees Donna Vekic and Victoria Azarenka meeting each other for the first time while Amanda Anisimova faces Madison Brengle.
Anisimova continues to make waves as the youngest and highest-ranked teenager in the WTA Top 100.
The 17-year-old, who is currently enjoying a career high of world No 23, grew up playing on a hard court and counts the surface as her favourite.
Zheng Saisai will look to make it two from two career meetings against Danielle Collins with USA qualifier Kristie Ahn facing-off against the third seed Elise Mertens.