Asked how excited she was, she blinked slowly, thought about it and sighed. She took care of No. 13 seed Jelena Ostapenko in the next match, dispatching her in straight sets.
The Spaniard lost 6-4 6-4 to Serena in the title match two years ago before turning the tables on the 23-times major winner to land her maiden grand slam title at last year's French Open.
Garbine Muguruza will take her place in the semifinals with a close-fought win.
The SW19 major has been kind to both sisters, who have turned its manicured lawns into something of a personal fiefdom since the turn of the century.
"This year has been amazing in terms of my play, playing deep into the big events actually".
Konta then felt the pressure serving at 4-5 in the opener, falling behind quickly 0-40, and couldn't save the game.
'I think today it came down on the day, and Venus played better than me.
Konta appeared relaxed and expectant as she entered Centre Court to face the veteran, and she tested Williams with her power game in the first exchanges.
World number 87 Rybarikova is a surprise semi-finalist, having never reached the second week of a grand slam tournament.
In another situation, Williams might be the sentimental favorite.
"Walking out there, I knew that I was playing against the home player, that maybe the crowd could get really loud", she said. But she's just not in the stadium.
"I don't know that I play exactly the same way she does".
More than a few people had money on a great former champion now in their sporting dotage fighting through the rounds and years for another tilt at the Wimbledon singles crown.
There was also a meaningful gap in the track records of the other semifinals, and it made a difference right away. She has won five singles titles and six doubles titles, all with her sister Serena.
"I played very well for sure", Muguruza said.
"I miss her so much", she said. "I think it was all credit to her". "I'm here to enjoy the match". "She likes to walk around and keep busy".
This will be the fifth Grand Slam final between women seeded 10th or lower.
Garbine Muguruza has sent World No.1 Angelique Kerber crashing out of Wimbledon and in doing so, knocked her off her perch as the best on the WTA Tour.
The American, who has dropped only one set all tournament, was too strong for her opponent from the baseline and was able to produce booming serves whenever Konta threatened.