Debuchy suffered ankle ligament damage in the 2-2 draw with Manchester City on Saturday and is undergoing more tests. British media reported he could be out for three months.
Forward Yaya Sanogo also stayed in London because of a hamstring problem.
The French coach will also be without injured left back Nacho Monreal while Calum Chambers, who missed training earlier on Monday, is being treated for tonsillitis and has a "50-50 chance" of playing.
"In defence we of course have the Mathieu Debuchy injury, and that puts us in a position where we do not want more (injuries),” said Wenger.
"Monreal didn't travel and Chambers is 50-50. Debuchy is out for a longer period. We don't know how long. Sanogo stayed at home with a little hamstring problem."
Wenger may now be forced to start 19-year-old right back Hector Bellerin.
"We have as well Bellerin, who I think is now ready to play," he said.