Teams involved (12)
Champions path (8): 2 automatic entrants, 6 third qualifying round winners
League path (4): 4 third qualifying round winners
Fixtures (16/17 & 23/24 August)
Qarabağ (AZE)/Ferencváros (HUN) vs Sheriff (MDA)/Viktoria Plzeň (CZE)
Bodø/Glimt (NOR)/Žalgiris (LTU) vs Ludogorets (BUL)/Dinamo Zagreb (CRO)
Maccabi Haifa (ISR)/Apollon Limassol (CYP) vs Crvena zvezda (SRB)/Pyunik (ARM)
Copenhagen (DEN) vs Trabzonspor (TUR)
Dynamo Kyiv (UKR)/Sturm Graz (AUT) vs Benfica (POR)/Midtjylland (DEN)
Union Saint-Gilloise (BEL)/Rangers (SCO) vs Monaco (FRA)/PSV Eindhoven (NED)
How does it work?
Teams play home and away with the aggregate winners progressing to the group stage draw on Thursday 25 August. If teams are level after 180 minutes, extra time and penalties will be played. There are no away goals.
All losing sides move into the UEFA Europa League group stage (draw on 26 August).