Williams, who won the Wimbledon title on her last two visits in 2015 and 2016, is now on an 18-match winning streak at the All England Club.
Having missed Wimbledon last year while she prepared to have her first child in September, Serena is in pole position to win her first Grand Slam crown since becoming a mother.
On Tuesday, the 36-year-old faces Italian world number 52 Camila Giorgi, who beat Russia’s Ekaterina Makarova 6-3, 6-4 to reach her first Grand Slam quarter-final.
Asked if it was a flawless display, Serena admitted she is never satisfied.
“I’m a perfectionist. I always find something wrong,” she said.
“It was a good win but it was tougher than the scoreline to be honest.”
Giorgi, 26, had failed to get past the third round of a major since the 2013 US Open.
But the 26-year-old underdog isn’t ruling out an epic upset against Williams.
“I don’t follow tennis, women’s tennis, but I think it will be a good match,” Giorgi said without a hint of a smile.
Serena’s 90th Wimbledon win of her career is the most among active female players.
Williams had made a tentative return to action following complications during daughter Olympia’s birth, struggling in her few appearances before pulling out midway through the recent French Open with a pectoral injury.
But the 23-time major winner’s blistering form and a series of shock results have paved the way for another Williams coronation at Wimbledon.
Garbine Muguruza, Maria Sharapova, Simona Halep, Petra Kvitova, Venus Williams, Caroline Wozniacki and Sloane Stephens have all been eliminated already.
Kiki Bertens took care of the last of the top 10 with a 6-3, 7-6 (7/1) victory over Czech seventh seed Pliskova.
It is the first time in Wimbledon history not one of the top 10 women’s seeds have reached the quarter-finals.
Bertens, who was contemplating retirement last year after losing her enthusiasm for the sport, is the first Dutch woman to reach the Wimbledon quarter-finals since Michaella Krajicek in 2007.
The 26-year-old faces German 13th seed Julia Goerges, who beat Croatian world number 55 Donna Vekic 6-3, 6-2 to seal her first Grand Slam quarter-final berth at the 42nd attempt.
‘It was ridiculous’
Elsewhere in fourth round action, Dominika Cibulkova launched a scathing attack on Wimbledon’s officials after a line call controversy marred her 6-4, 6-1 win against Taiwan’s Hsieh Su-Wei.
Cibulkova was furious when Hsieh successfully persuaded the umpire to replay a point that was initially called in the Slovakian’s favour and would have given her three set points in the opening set.
Hsieh’s protests to the umpire prompted the match referee to come on court to intervene as the argument lasted over seven minutes before the point was finally replayed, much to Cibulkova’s disgust.
“It was ridiculous what happened there. It never happened to me in my career,” Cibulkova fumed.
“After she was complaining, they were talking in Chinese, whatever language.
“Sometimes I’m also complaining because I think it was a wrong call. But it never happened to me that the umpire changed the decision.”
In her third Wimbledon quarter-final, Cibulkova faces former French Open champion Jelena Ostapenko.
Latvian 12th seed Ostapenko enjoyed a 7-6 (7/4), 6-0 win against Belarusian world number 50 Aliaksandra Sasnovich.
Former Wimbledon finalist Angelique Kerber stepped up her bid to return to the title match with a 6-3, 7-6 (7/5) win against Switzerland’s Belinda Bencic.
Kerber, who won the Australian and US Open titles in 2016, is seeded 11th—making her the highest ranked woman left in the draw.
Beaten by Serena in the 2016 final, Kerber takes on Russian 14th seed Daria Kasatkina, a 6-7 (6/8), 6-3, 6-2 winner against Belgian world number 47 Alison Van Uytvanck.
© Agence France-Presse