However, Williams lifted her intensity to level, before closing out the match to move a step closer to reclaiming the title she won in 2016.
Serena Williams celebrates winning a point. Her loss marks the first time in the Open era that any major has featured a quarterfinal round without a top-10 seed on either the men's or women's side, according to ESPN Stats & Information. Pliskova was beaten 6-3, 7-6 (1) by No. 20 Kiki Bertens, who eliminated Williams' sister, Venus, last week.
And she wasn't the only one to mastermind a comeback from a set down, either, as semi-final opponent Goerges also took the more hard route to ousting Bertens. After the first set, I just said, let's go three sets. It was a fearless performance that offered Williams one of her toughest tests since returning.
There are moments in which nothing at all seems different about Serena Williams, moments such as when she unleashed a 109 miles per hour service victor to even her Wimbledon quarterfinal at a set apiece, leaned forward and yelled, loudly as can be, "Cooome ooon!"
"I feel good, I felt like I did better today, I had to, but this is only my fourth tournament back so I don't feel any pressure and have to win this", she said. She missed Wimbledon a year ago because she was pregnant, going about 16 months between Grand Slam tournaments, so her ranking is just outside the top 180.
Ultimately, Williams found a way to win, 3-6, 6-3, 6-4, but Giorgi gave her all she could handle. This will be Bertens first quarter-final appearance at Wimbledon.
When Serena broke again for a 2-1 lead in the final set, the American whirled and pumped her arms.
Williams lost the first 6-3 on Centre Court.
Ostapenko was more efficient, serving her match out at love and converting her first match point with her 14th backhand victor. "I'm just here just to be here and to prove that I'm back".
But the title favourite is seven-time champion Serena Williams, seeded 25th after her lengthy maternity leave, and due to face Russian qualifier - and fellow mother - Evgeniya Rodina later on Monday. "Everybody has the same chances to win that match, and I'm looking forward to it".