Wenger confirmed that right-back Bellerin will miss the Champions League match against Bayern Munich with a groin injury.
The 20-year-old has been a revelation since replacing Debuchy in the first team earlier this year, but he will play no part at the Allianz Arena with the Gunners boss claiming the injury was just a “small problem”.
Debuchy will take Bellerin’s place against Bayern, while Debuchy’s teenage compatriot Jeff-Reine Adelaide, who featured in the pre-season Emirates Cup, has travelled and is in the squad.
But Wenger will now be without nine first-team players for the trip to Bavaria, where they will go into the game as Group F’s bottom side.
Theo Walcott (calf), Alex Oxlade-Chamberlain and Aaron Ramsey (both hamstring) remained sidelined as do more long-term absentees Jack Wilshere (leg), Danny Welbeck and Tomas Rosicky (both knee). Mikel Arteta and David Ospina are back in training but not in contention in Munich.
Wenger, speaking at his pre-match press conference, said: “I have confidence and trust in [Debuchy]. Physically he should be ready.”
Arsenal revived their hopes of making the knockout for a 16th straight season when they beat Bayern 2-0 last month.
And Wenger says he will send out a side to win the return match despite saying at the weekend he would “sign for a point now”.
“We need to give a similar performance to when we played in the first game” he said. “I expect Bayern to play offensively and try to put us under pressure. We have won everywhere in Europe and we will try to win this game.”