The two experienced central defenders Magnus Jensen and Croatian international Martin Erlic are ruled out for an extended period.
"I am neither a doctor nor a physiotherapist, but I can say that in both cases, it involves foot problems. Magnus will be out for a long time yet. I don't know exactly how long, but it is going to take a long time.
"As for Martin, it looks like it might take less time than for Magnus, but we are still not talking about a matter of weeks", said coach Mike Tullberg to the Danish media on Thursday afternoon.
Elias Olafsson, Magnus Jensen, Martin Erlic, Mikel Gogorza, and Junior Brumado are the club's long-term injured players. There is uncertainty regarding the severity of Beni Junior's injury.
Cho Gue-sung and David Martinez have had to return home from international duty, while Kjell Wätjen was injured shortly before the match against OB.
FC Midtjylland will face FC Copenhagen on 18 October in a clash of the two clubs at the top of the Danish Superliga.