Vincent Kompany's first competitive game as Anderlecht player-manager ended in a 2-1 home defeat to KV Oostende.
The 33-year-old, whose 11-year stint at Manchester City ended in May, started the match while former City team-mate Samir Nasri came on as a substitute after an hour's play.
The Brussels side forged ahead through Michel Vlap in the 12th minute but Oostende equalised six minutes later through Ronald Vargas.
Fashion Junior Sakala then put the visitors ahead with 15 minutes to go and Anderlecht had no response.