Maria Sharapova and Marion Bartoli - beaten semi-finalists in the French Open - have withdrawn from the Aegon Classic in Birmingham, starting 6 June.
Sharapova, a winner in 2004 and 2005 and twice more a finalist, has pulled out citing an illness while Bartoli picked up an injury at Roland-Garros.
"I am really sorry that I will miss all my amazing fans, but I will be back next year for sure," Sharapova said.
The remaining field includes Ana Ivanovic and Britain's Heather Watson.
Commenting on the withdrawal of the top two seeds, tournament director Patrick Hughesman added: "This is disappointing news for the tournament as Maria is very popular here in Birmingham.
"However we do still have world-class players competing at the event so it will be a great event and we're looking forward to it enormously."
The Birmingham tournament immediately precedes the grass court tournament at Eastbourne which runs from 12-19 June, with Wimbledon starting a day later.