The Czech broke Jovanovski twice in the first set before saving three break points in the second.
The unseeded Jovanovski hit 33 winners to only 13 for the 10th-seeded Dane. She will next face former French Open champion Svetlana Kuznetsova of Russia.
The 10th-seeded Wozniacki laboured for almost three hours in a struggle which ended in front of a standing-room only crowd as she lost to her 48th-ranked opponent in their first-round match.
The 19-year-old American is into the quarterfinals at a major for the first time.
At 19, Sloane Stephens is the only teen still standing after coming out on top of her third round clash with 18-year-old Briton Laura Robson, who is also rapidly improving and shocked eighth seed Petra Kvitova in the previous round.
After a week of setting age-related records and becoming the media darling of this year's Australian Open, the Japanese player bid farewell to the big stage for now after losing her third-round singles match on Saturday.
Date-Krumm, 42, had already become the oldest third-round contestant in 34 years, but she met her match in Serbia's Bojana Jovanovski who won a tense contest 6-2, 7-6 (7/3) in 1hr 46min.
Former World No.1 Caroline Wozniacki was pushed hard by Serbian qualifier Bojana Jovanovski in the first round of the Japan Open Monday, winning the match in a tense decider.
Maria Sharapova has backed to plans to silence tennis grunters even though the world number one is one of the worst offenders.
Recent top-10 player Andrea Petkovic of Germany has withdrawn from Wimbledon because of a persistent right ankle injury.