Sevilla's Yassine Bounou had been named on the teamsheets for the match and warmed up for the game as normal.
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He then walked out for the national anthems and appeared alongside his teammates.
However, there was confusion when he did not take his place in goal for the start of the match.
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Morocco made a late switch with Munir Mohamedi instead lining-up in goal.
No one seemed to know exactly what was going on and fans were confused as to what happened to Bounou.
There has been no official word from the Moroccan team as to why they made the late change.
It has been reported that he was taken ill shortly before the game began.
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The match was 0-0 at half-time with Morocco having a goal ruled out for offside just before the break.
Hakim Ziyech put the ball in the back of the net directly from a free-kick.
However, the officials judged that a Morocco player was impeding Thibaut Courtois, and in an offside position, even though he did not touch the ball.
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