Leeds are waiting for injury news on three players after the agonising 14-12 Super League defeat to Castleford at the Wish Communications Stadium.
With the World Club Challenge against Melbourne Storm on February 22 looming large, Ryan Bailey (knee), Brett Delaney (hamstring) and Zak Hardaker (concussion) picked up knocks as the Tigers secured a memorable derby win.
"I am not sure how long they will be out for," said McDermott of the trio.
"I don't think Delaney will be less than a week and we are not sure what the tweak is with Bailey's knee, whether it's a little nip of a cartilage or a bit of strain.
"Hopefully Zak will recover from his collision. I'd be wary of commenting on that incident but in general shoulder barges are all right - that has what this competition has ruled - but if it's head contact, it's head contact.
"I'm not saying it is with Rangi Chase - I'll have to look at it - but he knocked the kid out clean."
On the game, McDermott added: "Well done to Castleford. Both teams put in a really big effort.
"I haven't really got too much negative to say about us but I think I will be showing the players tomorrow in terms of what we need to do better. I think the game came down to some unfortunate errors.
"I don't think in general Castleford handled the conditions better than us - it was just unfortunate mistakes towards the back end that cost us."
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