Dundalk will face Riga FC in the Champions League first qualifying round.
Vinny Perth's side will welcome the first-time Latvian champions to Oriel Park for the first leg, before a trip to the 9,000-capacity Skonto Stadium.
Riga FC are competing in the Champions League for the first time since they were founded in 2014 by a merger of Caramba Riga and Dinamo Riga.
They won the Latvian league-and-cup double in 2018, and continue to lead the league this season - much like Dundalk in the League of Ireland.
They lost to CSKA Sofia on penalties in their only previous European fixture, in last year's Europa League first qualifying round.
Dundalk defeated Latvian opposition in Levadia Tallinn, 3-1, in last year's Europa League.
Dundalk must progress through four rounds of qualifying to earn a place in the Champions League group stages. They came within a game of achieving that feat in 2016 before losing to Legia Warsaw 3-1 on aggregate.
Celtic, the highest-ranked side in the draw, will face Bosnian champions FK Sarajevo as they bid to return to the group stages after last year's qualifying loss to AEK Athens.
The Scottish champions will host the first leg at Celtic Park, before travelling to the Asim Ferhatović Hase Stadium.
UEFA have handed Neil Lennon's side the added safety net of a bye to the third qualifying round of the Europa League should they fail to get past Sarajevo.
Normally teams beaten in the opening Champions League qualifier would enter the lesser competition at the second round, but the loser of Celtic's clash with the Bosnians will be spared action until the next round due to an odd number of teams entering the Europa League's champions' path.
Northern Ireland champions Linfield will face Norwegian giants Rosenborg, with the first leg at home at Windsor Park.
The first legs will take place on July 9 or 10, with the second legs scheduled for July 16 or 17.
Cork City, Shamrock Rovers and St Patrick’s Athletic will learn their travel plans when the Europa League qualifying draw is made later this afternoon.
Nõmme Kalju (EST) v Shkëndija (MKD)
Sūduva (LTU) v Crvena zvezda (SRB)
Ararat-Armenia (ARM) v AIK (SWE)
Astana (KAZ) v CFR Cluj (ROU)
Ludogorets (BUL) v Ferencváros (HUN)
Celtic (SCO) v Sarajevo (BIH)
Sheriff Tiraspol (MDA) v Saburtalo (GEO)
F91 Dudelange (LUX) v Valletta (MLT)
Partizani (ALB) v Qarabağ (AZE)
Slovan Bratislava (SVK) v Sutjeska (MNE)
Linfield (NIR) v Rosenborg (NOR)
Valur Reykjavík (ISL) v Maribor (SVN)
Dundalk (IRL) v Riga (LVA)
The New Saints (WAL) v Winners of the preliminary round
HJK Helsinki (FIN) v HB Tórshavn (FRO)
BATE Borisov (BLR) v Piast Gliwice (POL)