Central defender Steven Anderson is definitely out of the trip to Switzerland because of a hamstring injury.
Anderson has not travelled with the squad and remains in Perth along with midfielder Gary McDonald, who has been struggling with a niggling injury for several weeks.
Saints striker Stevie May is also likely to miss the match at the Swissporarena as he struggles to shake off a knock.
Luzern have new striker Marco Schneuwly available for Thursday's encounter after his recent signing from FC Thun.
Meanwhile, Wright has pinpointed midfielder Alain Wiss as the man who poses the biggest threat to his team.
“Wiss is a box-to-box player who has a knack of scoring goals so he will have to be watched closely,” Wright said.
“Overall, they are a team that likes to press high up the park but I feel we can use the experience we have gained in Europe to our advantage.”