Stuttgart - Andrea Petkovic withdrew from the Porsche Grand Prix with a thigh injury on Monday, leaving Germany without the best-ranked player at their top home event.
"Really sorry to announce that I have withdrawn from the Porsche Tennis Grand Prix in Stuttgart.
"It is one of my favourite tournaments and a decision I had to make in order to avoid any further risk for my health," the 11th-ranked Petkovic tweeted.
The statement came the day after Petkovic played singles and doubles in Germany's 3-2 Fed Cup semi-final defeat against Russia in Sochi.
Petkovic joined seventh-ranked Canadian Eugenie Bouchard and 2008 champion Jelena Jankovic of Serbia in a late withdrawal from the tournament which boasts eight top 10 players, led by three-time reigning champion Maria Sharapova of Russia.
Petkovic, who has never gone beyond the quarter-finals in Stuttgart, went out in the first round the past two years and suffered a severe ankle injury in a second-round game in 2012 which sidelined her for four months.