The German wrote on Twitter on Wednesday, "I really wanted to play the US Open but eventually I decided that two against one just isn't a fair competition."
World number two Karolina Pliskova followed Serena Williams and Naomi Osaka as she lost her third-round match at the Rod Laver Arena on Saturday to get knocked out of the ongoing Australian Open, while Angelique Kerber and Simona Halep avoided the trend.
A semifinalist in Melbourne last year, Pliskova lost 7-6 (4), 7-6 (3) to 30th seed Anastasia Pavlyuchenkova in a grueling contest of almost two and a half hours. With Osaka also out, two of the top three seeds will not take part in the pre-quarters of the Australian Open this year.
The two players broke each other in both the sets but Pavlyuchenkova took the edge in both the tie-breakers to show the WTA Brisbane-winner the doors.
Sixth seed Belinda Bencic, who was a semifinalist in the US Open last year, trod the same path as she suffered a major embarrassment of 6-0, 6-1 at the hands of Anett Kontaveit at the Margaret Court Arena.
Meanwhile, 2018 finalist Halep and 2016 Australian Open champion Angelique Kerber kept away from the losing trend. Halep won her third-round match in straight sets at the Rod Laver Arena. She defeated Yulia Putintseva 6-1, 6-4 to qualify for the Round of 16.
World number 38 Putinseva broke Halep once in each set, but the Romanian proved too strong for her. Halep broke her opponent thrice in the first set and twice in the second.
Kerber, on the other hand, won 6-2, 6-7 (4), 6-3 over Camila Giorgi to move to the fourth round in Melbourne for the fifth straight year. The former world number one and three-time Grand Slam champion was pushed to her limits by her unseeded Italian opponent in the match that lasted over two hours.