Darren Bent insisted he had to leave Aston Villa after too many "slaps in the face".
Brighton defender Greg Halford has agreed to extend his loan deal from Nottingham Forest until the New Year.
De Bruyne was training with his Belgium team-mates ahead of Friday's World Cup qualifier against Croatia when the incident occurred.
And Belgium boss Marc Wilmots must now wait to discover the extent of any damage 24 hours after losing centre-half Vincent Kompany for his side's final two qualifiers.
Wilmots' side go into the games with a five-point lead in Group A, and a draw in Zagreb will guarantee a place in Brazil next summer.
De Bruyne started two of Chelsea's first three games this season but was left out of the squad for Sunday's trip to Norwich amid criticism from Jose Mourinho.