Jonathan Erlich and Andy Ram have withdrawn from next week's Shanghai Masters tournament for the world's top eight men's doubles.
Erlich has not recovered from an elbow injury that has sidelined him since September and there are reports that he will fly to the US to see a leading specialist and possibly undergo surgery in the coming weeks.
"This is very frustrating," said Erlich. "I told Andy how sorry I am. I thought the pain in my elbow would keep me out for a week or two but it is now looking like something more serious."
The Israelis are currently ranked fourth in the ATP doubles table and have enjoyed their most successful year, winning the Australian Open, their first grand slam title, and the Indian Wells Masters.