McCoist will finalise his preparations for the campaign when his side play English Championship club County at the iPro Stadium this afternoon.
The SPFL League One champions have made steady progress during their summer tours of both the Highlands and Canada and the United States. And they are set to field their strongest side in their final friendly of the close season down in the East Midlands.
The Gers gaffer will be hoping for a confidence-boosting victory ahead of the Petrofac Training Cup match with Championship rivals Hibs at Ibrox on Tuesday evening.
But Ted McMinn, the former Gers and Rams player who will guest of honour at the game this afternoon, reckons they will need to perform at their very best to triumph.
He said: "This will be the hardest test that Rangers will have faced this summer. The Championship is a very good league and Derby are a very good side.
"I am sure that Ally and the Rangers players will all be looking to finish off their pre-season with a win ahead of their cup game against Hibs next week.
"But Derby are preparing for the new season as well and will be looking to improve upon the third-place finish they recorded last season and win promotion to the Premier League.
"They were desperately unlucky not to go up last season and have a point to prove. Rangers will have a huge travelling support at this game. But this will not be an easy match for them."
Rams great McMinn has told McCoist that the Scottish contingent in the home team - Craig Bryson and Johnny Russell - will be their danger men.
He said: "They have a strong contingent of Scottish players. Craig Bryson is one of their best players. I have no idea why neither of the Old Firm clubs snapped him up when they could.
"He had a clause in his contract stating that if a club came in with a £750,000 bid that he could be sold. Burnley offered that for him, but he has just signed a five-year extension. That shows you just how highly he is rated down here.
"Johnny Russell has also done well since joining from Dundee United. He had a slow start, but has settled in now.
"Derby have a vastly experienced manager in Steve McClaren and play nice football on their day. They are strong in every department of the field. But I am sure that Ally has done his homework and knows this.
"The Rangers fans are coming in huge numbers and I am sure they will enjoy their day. But their team will have to play well to give them a victory to celebrate."