The Reds start their campaign with a first-round tie against Forest at Oakwell, just 48 days after the East Midlands outfit were its last visitors.
The club have suffered four opening round exits in the League Cup in its various guises in the last six seasons.
But Struber insists that his priority is on the first league game of the season against Luton Town on September 12.
His only concern is that players play themselves into form to hand him some welcome selection dilemmas for the Hatters' test.
The Austrian said: "I can remember the last game (with Forest). We dominated the game and ended with a victory and the neccessary points.
"But Saturday is completely another situation. It is the Carabao Cup and for me, it is a big, big pre-season friendly game.
"The Carabao Cup is an interesting cup, of course. But for me, the Championship is the most important thing and the next game is a big test and every single player can show me a very good picture.
"The first 11 for our first game against Luton is not clear and I will (hopefully) see from every single player that he is ready for the Championship and on Saturday, everyone has the chance to show me a good game.
"I hope everyone understands that this is the last game before our season starts and we have big goals and the chance to come close with our style."
Barnsley will be without long-term injury victim Ben Williams, with the game coming too soon for midfield Romal Palmer, on the comeback trail following a knee problem.