McCarthy missed the 1-1 draw with Preston at the weekend after suffering a recurrence of a shoulder injury in training and is extremely doubtful for the match.
However, Warnock is boosted by the return of fellow defender Clint Hill who is available once again after serving a one-match ban on Saturday.
On-loan West Ham striker Freddie Sears is also set to return to contention after recovering from the groin injury which kept him out at the weekend.
The original clash between the two was due to take place on September 15 but was postponed due to a waterlogged pitch.
QPR midfielder Ben Watson is expected to return to the starting line-up for the derby clash.
Former Palace midfielder Watson, on loan from Wigan following his £2million switch from Selhurst Park in January, has missed the last two games through suspension after his recent dismissal against Reading.
Mikele Leigertwood could drop back to replace Peter Ramage at full-back to accommodate Watson's return.
Fellow midfielder Gavin Mahon faces a late fitness test after missing last Friday's home defeat to Leicester with a hip injury.
Manager Jim Magilton has no other new injury or suspension problems and is not expected to make many, if any, further changes to his side, who will climb into fifth place in the table with victory over their London rivals.
Sporting Life