"I hate losing. That's no secret", the 23-times major victor said after digging deep to deny Camila Giorgi a famous victory with a rousing 3-6 6-3 6-4 quarter-final comeback win over the unseeded Italian.
Next up for Williams as she tries to earn her eighth title at the All England Club and 24th Grand Slam trophy overall will be a match Thursday against No. 13 seed Julia Goerges of Germany, a 3-6, 7-5, 6-1 victor against No. 20 Kiki Bertens of the Netherlands. "I knew that after the first set I was like alright, lets go three sets".
The two-time Grand Slam champion from Germany defeated No. 14 Daria Kasatkina 6-3, 7-5 on Centre Court to reach the semifinals at the All England Club for a third time.
Williams was forced to withdraw from the fourth round of the French Open with a pectoral injury but has impressed in her bid to equal Margaret Court's record of 24 major triumphs.
With her easy power game in sync, Williams looked serene as she cruised to victory to set up a clash with Italy's Camila Giorgi, the fifth unseeded player she will have faced in a dream draw on her Wimbledon return.
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.
Williams hit serves up to 118 miles per hour, delivering 10 aces, including four in one game.
Giorgi had a bright start to the match, possibly catching Williams a little tired as she is still working her way back from the 14-month leave. She must be aggressive, with the right degree of control, and has to test the stamina of Williams who has so far won a stack of short points and rarely been pushed around court.
That was winning majors, and Williams enters the semifinals as the lowest-seeded player (25th) remaining in this year's Wimbledon tournament.
Having shaken off the rust following her lengthy lay-off after the complications with Olympia's birth, Serena is on the verge of a 30th Grand Slam final berth. Giorgi reduced the tally but the set proceeded with serve to end 6-3 for Serena. "Just the fewer the better for me!" It's 5-3 for Kerber and she will once again be serving for the match. "I feel like I'm back, but I still have a long way to go to get to where I was".
It's also the only Grand Slam tournament in the half-century professional era with zero top-10 seeds in the women's final eight.
Rapper friend Drake and fellow singer Justin Timberlake were among those rooting for her on Centre Court.
"It was great matches", Giorgi said in her postmatch news conference. I don't feel I have to win this; I don't feel I have to lose this. American with unrealized five break points and lost the first set, but never made such misfires.
Her opponent on Friday, Julia Goerges, is seeded 13th. She won 44 of the last 54 points she served.