Doku has returned to Ligue 1 club Rennes for treatment and been replaced by uncapped Johan Bakayoko (19), who plays for Dutch club PSV Eindhoven.
Belgium trained for the first time on Tuesday under new coach Domenico Tedesco (37), who named Kevin De Bruyne (31) as the team's new captain.
De Bruyne takes over from Eden Hazard (32), who retired from international football after Belgium failed to get past the group stage at the World Cup in Qatar.