Mousa picked up a hip injury on international duty with Belgium last week and that ruled him out for Saturday's derby against Chelsea.
"Dembele is making a slow return but Southampton is a possibility," said Andre ahead of training at Maribor's Ljudski vrt Stadium on Wednesday night.
Emmanuel Adebayor is out with a back problem while Andre reported that Gareth Bale hadn't travelled out to Slovenia for family reasons.
"Ade felt a pain in his back that he's had for quite some time," added Andre. "He had it last seasson and felt it in the first session after the Chelsea game.
"On Benoit, we're looking at two more weeks, hopefully, and Scotty and Kaboul are both working hard in recovery.
"Kyle Naughton was back on the bench against Chelsea and has a possibility of being involved."