The versatile Scotland under-21 international has returned to McDiarmid Park after helping the Saints to the Scottish Cup last season – and he is reaping the rewards with the club’s European campaign.
Middleton’s parent club Rangers are also in action on Thursday at Ibrox but his availability against LASK is a big boost to Davidson who was forced to travel without David Wotherspoon added to Eetu Vertainen’s transfer delay.
"Everyone apart from David Wotherspoon is across. He is still in his isolation period so hopefully we will get him back, possibly for the weekend,” the Saints boss explained. "Glenn is a big player for us and he is the type of player who can create things so I think with David not being with us, Glenn is a welcome addition to the team and gives me a few different options.”