Ronny Deila was left baffled after Jozo Simunovic was called up to the Croatian national squad.

The 21-year-old has been out injured since Celtic’s 3-1 win over St Johnstone in January, however he sustained the injury long before that.

Simunovic revealed that he played for over a month with a cracked bone in his knee and still hasn’t returned to training.

However, the centre-back has been called-up by Croatia’s under-21 manager for their upcoming European Championship games against Spain and Estonia.

As quoted by STV, Deila was baffled saying:

I can’t understand the call-up. He won’t be travelling. It will be some weeks before he is fit, but I’m not really sure how close.

Mark Runnacles/Getty Images Sport

He did indicate that he may return for the Scotish Cup semi-final against Championship side Rangers.

That’s five weeks away so that is a possibility.

Simunovic joined Celtic on deadline day at the end of the summer transfer window for a fee of around £3 million.

He’s made a lowly 17 appearances and missed 18 games due to his latest injury and an ankle injury he suffered in training after Celtic’s 2-2 draw with Ajax in the Europa League.

The defender scored his first goal against Dundee United, just over a week before discovering the severity of his injury, and will hope to form a partnership with January signing Erik Sviatchenko when he returns.

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