Seeded:
1 FC Girondins de Bordeaux (FRA)
2 AZ Alkmaar (NED)
3 FC Zürich (SUI)
4 FC Vorksla Poltava (UKR)
5 HNK Rijeka (CRO)/Aberdeen FC (SCO)

Unseeded:
6 PFC Cherno More Varna (BUL)/FC Dinamo Minsk (BLR)
7 FC Dacia Chisinau (MDA)/MŠK Žilina (SVK)
8 AEK Larnaca FC (CYP)
9 Istanbul Başakşehir (TUR)
10 FC Kairat Almaty (KAZ)/Alashkert FC (ARM)


Group 2
Seeded:
1 FC Kobenhavn (DEN)/Newtown AFC (WAL)
2 AS Saint-Étienne (FRA)
3 NK Lokomotiva Zagreb (CRO)/ PAOK FC (GRE)
4 CF Os Belenenses (POR)
5 Hapoel Beer Sheva FC (ISR)/FC Thun (SUI)
6 KR Reykjavík (ISL)/Rosenborg BK (NOR)

Unseeded:
7 WKS Śląsk Wrocław (POL)/IFK Göteborg (SWE)
8 FK Jablonec (CZE)
9 Skonto FC (LVA)/Debreceni VSC (HUN)
10 FC Spartak Trnava (SVK)/Linfield FC (NIR)
11 FC Vaduz (LIE)/Nomme Kalju FC (EST)
12 ASA Târgu Mureş (ROU)

Group 5
Seeded:
1 Vitória SC (POR)
2 Trabzonspor AŞ (TUR)/FC Differdange 03 (LUX)
3 Athletic Club (ESP)
4 FC Krasnodar (RUS)
5 NK Koper (SVN)/HNK Hajduk Split (CRO)
6 Jagiellonia Białystok (POL)/AC Omonia (CYP)

Unseeded:
7 ŠK Slovan Bratislava (SVK)/University College Dublin AFC (IRL)
8 SCR Altach (AUT)
9 PFC Beroe Stara Zagora (BUL)/Brondby IF (DEN)
10 FH Hafnarfjördur (ISL)/Inter Baki PIK (AZE)
11 FK Mladá Boleslav (CZE)/Stromsgodset IF (NOR)
12 FK Jelgava (LVA)/FK Rabotnicki (MKD)