His Side FC Zurich currently lie in 2nd place in group L after two games including a surprise home victory against Turkey's Osmanlispor.
Zengaylay, who had surgery a fortnight ago on his arm, was in high high hope to be ready for this match. However, he needed to have a follow-up procedure done just this week, effectively ruling him out for this leg.
International teamate, Alfred Zagallo Sankoh also suffered an arm injury over the weekend that will also see him on the sidelines for at least six weeks.
Zengaylay's FC Zurich teammate, Davide Chiumiento, told JakatoSports that Zengaylay will be missed. "He's[Zengaylay] so quickly become an integral part of the team and is the DNA of our stability defensively.
He has so much composure on the ball and reads the game so well it's going to be hard to replace that on the pitch."
If FC Zurich are able to pick up any points against bottom-of-the-table FC Steaua, it could put them in a great position to qualify for the next stage of the stage of the competition.