Petra Kvitova will not play the WTA event at Birmingham, and is in some doubt for Wimbledon.
The 29-year-old Czech also withdrew from the French Open because of an arm injury, and said she is not yet sufficiently recovered.
"I'm working really hard to get back as soon as possible," Kvitova said on social media. "And—of course—keeping everything crossed for Wimbledon."
Hi guys! Quick update for you.— Petra Kvitova (@Petra_Kvitova) June 12, 2019
Unfortunately Birmingham is too soon, but I'm working really hard to get back as soon as possible and - of course -keeping everything crossed for @Wimbledon ???? https://t.co/GjDArQCYwE
The world No. 5 was the two-time defending champion, winning it in just her second event back from a knife attack in her home that her left hand badly damaged, and then defending the title.
According to a Czech federation spokesperson, Kvitova is rehabbing the muscle injury, and will not make any further decisions until just before Wimbledon.
Madison Keys has also withdrawn with injury. The 24-year-old reached the French Open quarterfinals, and had won the WTA event at Charleston. Bianca Andreescu, who has not completed a tournament since her title run at Indian Wells, withdrew upon experiencing more shoulder pain during her first round at the French Open.
Meanwhile, Marketa Vondrousova, who reached the finals at Paris, had previously withdrawn citing the need to rest further.
The field still has the top three players in the WTA rankings—Naomi Osaka, Ash Barty and Karolina Pliskova, who has received a wild card. Venus Williams has also received a wild card into the grass-court warmup.