Belgium thrashed Luxembourg 5-1 in Genk on May 26 as Marc Wilmots' squad began their final FIFA World Cup preparations.
However, the result will not stand as an official FIFA-recognised friendly after Wilmots used seven substitutes during the match.
The Belgium coach made five alterations at half-time to give as many of his players some game time and the sixth change saw Divock Origi replace Lukaku just after the hour.
Sides are only permitted to use six subs in friendlies under FIFA regulations, which were broken when Nicolas Lombaerts was introduced in the 77th minute.
"This match has subsequently been declared unofficial due to Belgium exceeding the maximum number of substitutes permitted," FIFA confirmed on Wednesday.
That decision means Januzaj will have to wait until the weekend against Tunisia to earn his first official international cap, having not been used in Belgium's 2-0 victory over Sweden on Sunday.
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