But Williams rallied to win 3-6 6-3 6-4 on Centre Court and then insisted she was never anxious.
Williams dug deep to deny Camila Giorgi a famous victory with a fighting 3-6 6-3 6-4 quarterfinal comeback win over unseeded Italian on Tuesday (Wednesday NZ Time).
The seven-time champion, who missed the tournament a year ago, was outplayed by Italian Giorgi in the first set, but rallied to win 3-6 6-3 6-4 on Centre Court.
At a recent Wimbledon press appearance, Serena Williams responded to comments made by fellow tennis player Madison Keys about how Williams, as the undisputed greatest player in her sport, always has to deal with her opponents bringing their absolute best in a match.
Williams, a seven-time Wimbledon champion, was in danger of a stunning exit after world No 52 Giorgi became the first player in this year's tournament to take a set off the former world No 1.
A double fault and a superb Goerges forehand created break point in Bertens' next service game but she was again up to the task, producing two big serves.
Airbus: engagement de coommande d'A220 par JetBlue
De plus, la compagnie aérienne a converti 25 de ses commandes actuelles d'Airbus A320neo en commandes d'A321neo . Le siège du programme et la ligne d'assemblage principale resteront basés à Mirabel, au nord de Montréal.
"To really share this feeling with her (Kerber), with a nation, I think that's something which is pretty special", she said.
With all the top 10 women's seeds now out, Williams is hot favourite to win an eighth title. "This is only my fourth tournament back", said Serena Williams, who has won all three of her previous meetings with Giorgi.
"I'm here just to prove that I'm back, and I feel like I'm back".
From then on, the result felt inevitable as she served beautifully, levelling the match and then, after a stunning backhand to break for 2-1 in the decider, she eased through the set, serving out to love to take her place in the last four.
"I don't know. Just stay tuned, right?" she said.
With two players that possess as much firepower, especially on serve as the Czech and the Dutchwoman, there didn't figure to be a lot of break chances, but it was Bertens who had the first opportunity.
Dutchman takes Tour stage - Martin in the bunch
Greg Van Avermaet retains the yellow jersey and remains first in the general classification for the fourth consecutive stage. Bernard Hinault went on the attack, even in retirement, at defending champion, Chris Froome , over his salbutamol case .
Williams could have played with baby Alexis strapped to her back in a papoose and still rolled over Rodina.
Having crashed out in the first round at Wimbledon for five consecutive times, Goerges' emotions spilled over at the end of the match after she embraced Bertens at the net.
Ostapenko is within sight of a second grand slam crown in 13 months after surging into the Wimbledon semifinals for the first time.
Here is a look at some of the key talking points for the women's last-four matches.
Julia Goerges of Germany celebrates breaking the serve of Kiki Bertens of the Netherlands during their women's quarterfinal match at the Wimbledon Tennis Championships in London, Tuesday July 10, 2018.
Seeded 11th, Kerber seems to be approaching something close to her 2016 peak, when she won her two grand slam titles and reached the final at Wimbledon.
Trump to talk to Russia's Putin about substantially reducing nuclear weapons
A US official said Trump would be ready to talk about New Start if Putin raised it, but it was not a big USA priority. Mueller III's investigation into potential collision between members of the Trump campaign and Russian officials.
The 12th seed will face Dominika Cibulkova next after the Slovakian continued her defiant run with a 6-4 6-1 victory over Su-Wei Hseih.