The Manchester City captain injured his thigh in October and was originally set for a three-week absence, but Lieven Maesschalck has estimated he will be out for another two months
The Manchester City captain was expected to be out for three weeks after sustaining a thigh injury against Everton last month.
However, Kompany has already missed seven matches and the Belgian FA have now sent their physio to assess the defender.
Maesschalck told Sky Sports: "I think Vincent is going to be ready in several weeks. We will do everything we can to bring back Vincent in a good way for a long time.
"First of all he had a rupture, a tear into the abductor and then also he has bad luck with a small thing on the front side now, so it's everything together.
"It's not really so long - eight weeks [the potential length of Kompany's lay-off] is nothing in the time of injury; you must respect biology."
Belgium take on Colombia on Thursday before facing Japan next Tuesday.