Birmingham City striker Obafemi Martins is out for the rest of the season with a stress fracture of the leg.
Martins is on loan from Russian side Rubin Kazan and scored the winner in the shock win over Arsenal at Wembley in February.
But he has not played since appearing against Wigan in mid-March.
Blues boss Alex McLeish said: "Oba has had surgery and it's a blow for him and a blow for us and we wish him a speedy recovery.
"He passed his medical and everything was fine for six weeks but then it became obvious something was not quite right.
"The problem has crept up on him during the past month or so and a stress fracture was diagnosed."
McLeish is yet to make a decision on a permanent deal for the Nigeria international.