Saibari slipped behind two Scotland defenders and Brahim Diaz dropped the ball over the top to him. Saibari gathered and blasted it into the top left corner of the net, well outside the reach of goalkeeper Angus Gunn.
Morocco, which reached the semi-finals at the last World Cup in Qatar, drew 1-1 with Brazil in its Group C opener. Scotland, which hasn’t got out of the group stage in its previous eight previous World Cup appearances, beat Haiti 1-0 in its first match.
Saibari also scored Morocco’s goal against Brazil.
Morocco nearly scored another in the 52nd minute when a header by Bilal El Khannouss off Achraf Hakimi’s corner kick was battled down by Gunn.
Scotland had a chance in first-half stoppage time when Andy Robertson sent a cross at John McGinn, who couldn’t get a foot on it near the back post.
As Scotland pressed for an equalizing in the closing minutes, Morocco had a pair of good chances to add to their wide both both missed the target. (AP)