Former Hoops striker McGhee had said: "We do not necessarily have to beat Celtic on Saturday to finish fourth in the SPL and make Europe.
"We do have to beat Raith in the cup.
"We need our strongest squad to be fit for Tuesday so I will need to be careful who I pick.
"It might be I'll make changes for Saturday to make sure the best team is clear to face Raith. It's something I have to look at carefully."
McGhee is under pressure to beat Raith, with the Dons having crashed out of the Scottish Cup to lower league opponents more than once in recent years.
Any attempt to rest players may not go down well with Rangers, whose lead over Celtic at the top of the SPL was cut to eight points on Wednesday night.