Roberto Martinez slammed Birmingham's Liam Ridgewell for the tackle that could rule Wigan's James McCarthy out of the Ireland squad.
The Latics chief was left fuming after 19-year-old McCarthy was left nursing more damage to his left ankle when Ridgewell dived in on him in the final stages of Saturday's 1-0 defeat at St Andrews.
McCarthy is hoping he will be able to line up for the Republic against Brazil at Arsenal's Emirates Stadium on Tuesday, but Martinez was not as confident when discussing the incident.
He told the Evening Post: "It was a leg-breaking challenge - there are no two ways about it.
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It is difficult to understand how Ridgewell missed the ball, because it was not moving.
"For the referee not to at least caution him was strange.
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But James is a fit, young man and that allowed him to react well to the challenge.
"It will difficult for him to be fit for tomorrow, because it was a horrendous challenge that he suffered.
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Hopefully the ankle will get a lot better - we'll just have to wait and see."