The seven-time champion faces Italian world number 52 Camila Giorgi for a place in the last four in only her fourth tournament since giving birth to daughter Olympia in September.
After sweeping aside Russian Evgeniya Rodina 6-2 6-2 on Centre Court, Williams, 36, had an ominous warning for her rivals.
She said: “I feel like I’m getting to where I want to be.
“For me, there’s so much further I want to go to get back where I was, and hopefully go beyond that.
“I’m getting there. I don’t think I’m there yet. I feel like it takes time to get there.
“I’m always striving for perfection. There’s a lot of things that, I don’t know if you can tell, but I really need to work on. Hopefully I can get there.”
“Whether it’s Miss or Mrs Williams, it’s still the same Serena”
— Wimbledon (@Wimbledon) July 9, 2018
Williams, currently the world number 181 having slipped down the rankings following her maternity leave, is the lowest-ranked player to reach the Wimbledon quarter-finals in the open era.
Seventh seed Karolina Pliskova’s defeat to Kiki Bertens means that none of the top eight are in the quarter-finals for the first time since the All England Club introduced seedings in 1927.
Bertens will meet German 13th seed Julia Goerges, who beat Donna Vekic 6-3 6-2.
Dominika Cibulkova, whose straight-sets win over Hsieh Su-wei was overshadowed by a lengthy argument with umpire Zhang Juan over a disputed point, faces last year’s French Open winner and 12th seed Jelena Ostapenko.
Angelique Kerber, seeded 11 and now the highest-ranked player left in the tournament, beat Belinda Bencic of Switzerland 6-3 7-6 (7/5) and will meet Daria Kasatkina, who ended Alison Van Uytvanck’s run with a 6-7 (6/8) 6-3 6-2 win.
Provided by Press Association Sport
She hasn’t dropped a set yet, has spent less than five hours in total on court through her first four matches, is averaging a 24 winner-count in each round, yet somehow Jelena Ostapenko has been flying under the radar at Wimbledon this fortnight.
The Latvian 2017 French Open champion, lost in the first round of her title defence in Paris six weeks ago, but is back on a mission on the lawns of south-west London and booked herself a spot in the quarter-finals with a 7-6 (4), 6-0 over Aliaksandra Sasnovich on Monday.
After falling behind 2-5 to Sasnovich – who knocked out Petra Kvitova in the first round – Ostapenko won 11 of the next 12 games to wrap up the win and reach the last-eight at Wimbledon for a second consecutive year.
The 21-year-old, who next faces unseeded Slovak Dominika Cibulkova, won the Wimbledon junior title in 2014 and has an aggressive style that can be terrifying on grass.
Ostapenko’s shock first-round loss to Kateryna Kozlova at Roland Garros in May saw her drop out of the top-10. She parted ways with her coach of just six months, David Taylor, after Paris and added Glenn Schaap to her team, to work alongside her mother. Schaap had just split with Anett Kontaveit, also after the French Open.
“I’m just trying to forget it as quick as I could and I just want to have a good tournament here.”
That she is having.
The young Latvian has been her fiery self so far this Wimbledon, and has been particularly ruthless on return, winning 20 of 38 return games on her opponents’ serve.
With all top-10 seeds crashing out before the quarter-finals, Ostapenko is the second-highest ranked player still standing in the draw, behind No. 11 Angelique Kerber.
She has been witnessing all the high-profile upsets from afar but is trying to remain focused on her own path.
“I’m not surprised anymore because every day something strange is happening in a draw and some surprises. Just now Simona lost, that was a big upset probably. But I’m still in the draw and I’m playing and just trying to focus on myself,” Ostapenko said after her third round on Saturday.
“I’m just trying to focus on myself because I think that when I play well I can beat anyone.”
Does she have an explanation as to why all these top-10 players fell early?
“I don’t know. I think grass is always a tricky surface – for me I really like it but probably for the other players it’s hard because you never know what to expect because some players can play better on grass and the bounces are not always the same, so I don’t know what’s happening,” she replied.
Ostapenko says her current level is similar to how it was at the French Open last year but believes the grass is even better for her game.
Her first tournament with Schaap was Eastbourne, right before Wimbledon, and she says they’ve already struck up a solid dynamic.
“It was a good almost half year working with David [Taylor] but after the French Open we decided to not continue working because it wasn’t working anymore,” said Ostapenko.
“For me I think everything is positive that I changed the coach. When I started to work with Glenn, he told me some things and I really like those things and they were working very well. And I think it helps my game a lot what he’s saying.”
Ostapenko has now had three different coaches working alongside her mother within the last 12 months – Schaap, Taylor, and Anabel Medina Garrigues, who was in her corner during her Roland Garros title run last year.
It may not always be easy listening to all these different voices within one’s camp and Ostapenko admits it doesn’t always go too well.
“It depends, if I have respect and I saw what that coach did before then I have respect straightaway and I listen to everything he says but if I see that things aren’t really working so well then I’m doubting, and maybe I listen but inside I have this feeling that it’s not working and like I don’t need to listen to it probably,” she says with a smile.
With Ostapenko and her compatriot Ernests Gulbis both making the second week at Wimbledon this fortnight, it’s the first time in history that multiple Latvian players have made it this far at the same Grand Slam.
“It’s great to see him doing this well because I think he’s such a talented player and he can play on a very high level,” Ostapenko said of Gulbis.
“I hope he’s going to go even further in the tournament.”
As we enter the Wimbledon last-16 stage on Monday, only six seeds are still standing in the women’s draw and only one of them is a top-10 player – Karolina Pliskova.
On the men’s side, five of the top-10 seeds were sent packing, although Roger Federer, Rafael Nadal, and 12th-seeded Novak Djokovic are all still alive.
There has been so much commotion regarding the seeds carnage at the All England Club this fortnight but perhaps we should stop and ask ourselves what exactly constitutes an “upset”?
Is it an upset any time a player defeats a higher-ranked opponent? When a three-time Grand Slam champion like Stan Wawrinka, whose ranking is down to 224 because he was sidelined with an injury, defeats sixth-seeded Grigor Dimitrov, should we really call that an upset?
Since the start of March, Dimitrov has made just one semi-final on tour and his Wimbledon preparations consisted of two matches, one tight win over Damir Dzumhur at Queens, followed by an easy defeat to Djokovic in the next round. Granted Wawrinka hasn’t been winning much either but it was hardly a surprise that the Swiss won.
World No. 2 Caroline Wozniacki lost to Russian lefty Ekaterina Makarova in the second round. Makarova has 12 top-10 wins posted at the Slams throughout her career. Only three active players have won more: Serena Williams, Venus Williams and Maria Sharapova. Again, is that really an upset?
Fantastic follow-ups: 8 of the 9 who defeated a Top 10 seed are into the 2nd week.
Hsieh (No.1 Halep)
Makarova (No.2 Wozniacki)
Van Uytvanck (No.3 Muguruza)
Vekic (No.4 Stephens)
Bencic (No.6 Garcia)
Sasnovich (No.8 Kvitova)
Bertens (No.9 Venus)
Rodina (No.10 Keys)#Wimbledon
— WTA Insider (@WTA_insider) July 7, 2018
Form, previous results, head-to-heads, confidence levels, weather conditions… so many things contribute to a specific outcome of a match on a given day. The closer we pay attention — in most cases — the more a result will make sense.
While surely there have been unexpected shocks, like Petra Kvitova losing in the first round to Aliaksandra Sasnovich, or Marin Cilic blowing a two-sets-to-love lead in a rain-interrupted second round against Guido Pella, the idea that an entire draw is collapsing is not an accurate indication of what’s been really happening.
Eight of the nine players to defeat women’s top-10 seeds have made it into the second week. So those so-called “upset-makers” have actually backed up their wins throughout the opening week.
Is it such a bad thing that the level is so close in tennis that the number next to a player’s name is becoming less and less significant?
I, for one, am more engaged when I don’t already know who the winner of a certain match, or tournament, is going to be. It’s time we embrace the “chaos”, and reexamine our way of how we look at upsets.