The second qualifying round games will be played over two legs on the 16th or 17th of July. The second leg which is set to be played in the Polish capital is scheduled for either the 23rd or 24th of July.
The 16 victorious sides must navigate the third qualifying round and a play-off to reach the group stage.
The likes of Olympique Lyonnais, FC Zenit St Petersburg and PSV Eindhoven await them in the third qualifying round.
The second qualifying round draw in full is:
Neftçi PFK (AZE) v KS Skënderbeu (ALB)
FC Steaua Bucureşti (ROU) v FK Vardar (MKD)
FC Viktoria Plzeň (CZE) v FK Željezničar (BIH)
FC Sheriff (MDA) v FK Sutjeska (MNE)
Birkirkara FC (MLT) v NK Maribor (SVN)
Sligo Rovers FC (IRL) v Molde FK (NOR)
IF Elfsborg (SWE) v FC Daugava Daugavpils (LVA)
HJK Helsinki (FIN) v JK Nõmme Kalju (EST)
FK Ekranas (LTU) v FH Hafnarfjördur (ISL)
The New Saints FC (WAL) v Legia Warszawa (POL)
Celtic FC (SCO) v Cliftonville FC (NIR)
GNK Dinamo Zagreb (CRO) v CS Fola Esch (LUX)
Győri ETO FC (HUN) v Maccabi Tel-Aviv FC (ISR)
FC BATE Borisov (BLR) v FC Shakhter Karagandy (KAZ)
FC Shirak (ARM)/SP Tre Penne (SMR) v FK Partizan (SRB)
ŠK Slovan Bratislava (SVK) v PFC Ludogorets Razgrad (BUL)
FC Dinamo Tbilisi (GEO) v FC Lusitans (AND)/EB/Streymur (FRO)