The former reserve team coach took over last week from Lucien Favre who resigned after a five-game losing start to the Bundesliga and has revived their fortunes with two league wins.
"Manchester City are very good and have outstanding players but it is not an overwhelming opponent," Schubert told reporters on Tuesday. "We won't freeze in awe but instead want to show what we've got on the pitch."
"What we need to do is run a lot to reduce the distance between the parts of our team, to keep them small."
Schubert said he did not want to speculate about which City player may miss the game with injured skipper Vincent Kompany, keeper Joe Hart and midfield powerhouse Yaya Toure all doubtful.
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"It is not decisive for us who is injured at City because tomorrow, whoever plays for them will challenge us for everything we have," he said.
The 44-year-old Schubert has no European experience and precious little experience in the Bundesliga.
But he sounded upbeat as Gladbach try to get some points on the board after losing their Group D opener under Favre at Sevilla.
"The beautiful thing about football is that with a good plan and a united team you could beat an arguably stronger opponent and we want to try that on Wednesday," he said.
"After all I am still unbeaten against City," he joked, referring to a 1-1 draw between the two youth teams recently.
(Reporting by Karolos Grohmann; editing by Martyn herman)
