Wigan defender Ramis has been ruled out for the rest of the season because of a knee ligament injury.
The 28 year old was taken off on a stretcher in Saturday's 1-1 draw at Fulham and scans show he has ruptured his anterior cruciate ligament in his right knee.
"Nothing can disguise the fact this is a massive blow because Ivan is a key member of the group," said Latics boss Roberto Martinez.
"But we're relieved it is not as severe as we feared it could have been."
Meanwhile Martinez is expected to try to bring in cover for Ramis in the January transfer window.
"The most important thing now is to think of Ivan's welfare, get the operation completed, and for him to begin his rehabilitation," added Martinez.
"Ivan is a very strong and positive character and he is determined to return to fitness as soon as he can.
"He will receive the best possible medical rehabilitation as the club ensures to have him return as an even stronger footballer."