The Football Association was reportedly keen to entice the Manchester United winger to commit his international future to England, though the 19-year-old would not have been eligible to do so for another four years.
Januzaj qualified to represent a host of countries, including Albania, Turkey and Serbia, but has confirmed his intention to play for the country of his birth and could now feature for Marc Wilmots's men at the World Cup this summer.
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"If a player isn't eligible to play for England until 2018 then what's the problem if he goes and plays for someone else?" the 66-year-old told the media.
"I'm sorry but sometimes I don't see what the fuss is about.
"He's not English anyway - let's be fair. We can argue that, under the current Fifa rules, by 2018, he might be eligible to play for England.
"But how can you be upset in 2014 if he goes and plays for one of the other countries that he's actually eligible for? He was born and brought up in Belgium. We can't be disappointed by that.
"It would be very different if he was available to play for us and we passed up the opportunity and he went to play for Belgium - the question would be relevant - but it's not relevant when he can't play until 2018."