A beaten semi-finalist at the All England Club in 1996, the 42-year-old overcame Romania's Alexandra Cadantu, who is almost half her age, to set up today's match.
Hundreds of Japanese fans were flocking to cheer her on in the fourth match on Court One, where she faces the unenviable task of ending world number one Williams' 33-match winning streak.
"She's so strong now," Date-Krumm said of the American. "It's very, very difficult to beat her. I have never played her.
"I played with [her sister] Venus two years ago here and this year in Miami. But, of course, between Venus and Serena there is a big difference.
"She has more power and she has more, of course, speed. She has confidence. She has everything.
"I need to try, just try my best. I hope I can stay more than one hour, one hour and a half. I will try my best."
The winner of that clash will face Sabine Lisicki or Samantha Stosur, who were billed second up on Centre Court.
Former champion Petra Kvitova was returning to resume her clash with Russia's Ekaterina Makarova.
The Czech, who won the Wimbledon title two years ago, was in danger of tumbling out of the tournament when bad light halted play last night.
Makarova, the 25th seed, led 2-1 with a break of serve in the deciding set when the players came off court just before 9pm.
Sloane Stephens and Petra Cetkovska took a set apiece before they came off due to the light, while Puerto Rico's Monica Puig was a set and a break down against Eva Birnerova.
Yesterday was a rain-affected day at the All England Club, where world number seven Angelique Kerber crashed out.
The German, a semi-finalist last year, was defeated 3-6 7-6 (8/6) 6-3 by world number 46 Kaia Kanepi.
To make matters worse, Kerber was subjected to vile abuse on social media after she saw the match drift away.
Elsewhere, Maria Sharapova's conqueror Michelle Larcher de Brito bowed out to Karin Knapp 7-5 6-2.