The Finland international has been dogged by injury problems, most notably a knee complaint for the past three seasons and Blues boss Steve Bruce admitted Forssell needs to go under the knife sooner rather than later to try and minimise the time he will be sidelined.
Bruce said: "Mikael will go into hospital on Monday. It looks like he has got a hernia problem and we will do something about it as quickly as we possibly can. He will miss the Manchester United and Blackburn games. These things usually take three to four weeks."
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