At least three clubs qualified for the new-look 36-team Champions League after coming through the second legs of their play-offs on Wednesday.
They are: Young Boys, Red Bull Salzburg and Sparta Prague.
Young Boys claimed a 4-2 aggregate win over Galatasaray after recording a 1-0 away victory.
Alan Virginius scored the winner in the 87th minute in Turkey.
Salzburg will be making their sixth straight appearance in the main phase of the competition, following a 1-1 draw at home to Dynamo Kyiv.
They wrapped up the tie 3-1 on aggregate and will be one of two Austrian sides in Thursday’s draw, joining Sturm Graz.
Sparta Prague also made it through qualifying as a 2-0 win over Swedish side Malmo completed a 4-0 overall triumph for the Czech champions.
The four remaining spots will be filled on Wednesday.