The Porsche Tennis Grand Prix suffered a serious blow on Monday morning when the news was revealed that two of the top stars, Dominika Cibulkova and Caroline Wozniacki had been forced to withdraw from the event.

Wozniacki pulled out of the draw, citing a left wrist injury, and was replaced by British lucky loser Johanna Konta in an opening round match against Estonian Kaia Kanepi. Cibulkova pulled out of Stuttgart because of an Achilles injury, and was replaced by German lucky loser Mona Barthel.

Sad I had to withdraw from Stuttgart today. Sorry to everyone who was gonna come out to support me!

— Caroline Wozniacki (@CaroWozniacki) April 21, 2014

Defending champion Maria Sharapova is seeded sixth this year, and is in a draw that features some of the top competitors in the WTA tour, with the top seed being world No. 3 Agnieszka Radwanska.

The Porsche Tennis Grand Prix is Europe’s oldest indoor women’s event and is the lone indoor clay tournament on the calendar. It takes place between April 21-27.