And after Williams came up with a comeback to beat 52nd-ranked Camila Giorgi of Italy 3-6, 6-3, 6-4 on Tuesday, she headed off Centre Court with her right index finger aloft.
Goerges also recovered from a set down to beat Kiki Bertens, 3-6, 7-5, 6-1.
The 26-year-old, who was contemplating retirement last year after losing her enthusiasm for the sport, was the first Dutch woman to reach the Wimbledon quarter-finals since Michaella Krajicek in 2007.
"She is not a human; she is just a hero", Bartoli of Williams, who's seeking her eighth championship at the All England Club and 24th Grand Slam title just 10 months after giving birth to her first child. In a tournament where the top 10 women's players have been eliminated, Giorgi hadn't faced a seeded player since her first-round win over No. 21 Anastasija Sevastova.
Ostapenko is within sight of a second grand slam crown in 13 months after surging into the Wimbledon semifinals for the first time.
He will meet Rafael Nadal at a grand slam for the second time in a matter of weeks after the Spaniard eased past del Potro in the French Open semifinals en route to his 17th major.
Kerber, runner-up at the All England Club two years ago, as well as the 2016 Australian Open and US Open victor, looks on a mission to atone for a disappointing season in the slams in 2017. "I'm just here just to be here and to prove that I'm back". "It was really ridiculous for me".
Pliskova, at seven, was the highest seed to reach the fourth round after an extraordinary first week of upsets but her hopes of further progress evaporated on a stiflingly hot Court Two.
The 90th Wimbledon win of her career - the most among active female players - means Serena, now 181st in the WTA rankings, will return to the top 100 next week.
Kerber takes on Latvia's Jelena Ostapenko in the other semifinal.
However, Kerber, beaten by Serena in the 2016 Wimbledon final, doesn't believe Ostapenko will be able to play completely free of anxiety with the title match within touching distance.
The Queen is back, with Tuesday's win guaranteeing that she will jump from 181 to at least 51 when the new rankings are announced next week.
On Monday, the 36-year-old needed just 62 minutes to dispatch qualifier (and fellow mom) Evgeniya Rodina, 6-2, 6-2.
Although All England Club chief executive Richard Lewis said there has been no approach from the White House over a possible visit, both players were asked about it following their victories.