Petra Kvitova could face a race against time to be fit for Wimbledon after withdrawing from the Birmingham Classic with an injury.
Two-time Wimbledon champion Kvitova, the world number five, pulled out of her first-round French Open match in May due to an arm problem.
Kvitova won the 2017 Birmingham tournament - her first triumph since returning to tennis after she was stabbed by an intruder in her home in December 2016 - and prevailed again in last year's final with Magdalena Rybarikova.
However, she will not be able to defend her title for a third successive season.
"Unfortunately Birmingham is too soon," Kvitova posted on her official Twitter account.
"I'm working really hard to get back as soon as possible and keeping everything crossed for Wimbledon."
"I have the best memories of Birmingham," the 29-year-old said in a video tweeted by the LTA.
"It was the first place that I won a title after I came back from my injury. I always have the best time there and I hope next year I will see you on the beautiful grass courts."
While Kvitova will not take part, world number three Karolina Pliskova, along with US open champion Naomi Osaka and French Open winner Ashleigh Barty will all play in the event, which begins on 15 June and serves as a warm-up for Wimbledon, which starts on July 1.