Uefa face the nightmare prospect of Celtic and Linfield FC meeting in a Champions League qualifier on 12 July.
Brendan Rodgers' side, who were seeded in Monday's (19 June) draw, will enter the competition at the second qualifying round where they will meet the Northern Irish champions or San Marino's SP La Fiorita.
Should Linfield jump that hurdle, they are scheduled to host the Scottish champions in the first leg at Windsor Park on the 11 or 12 July – the latter being the date of the traditional Ulster Protestant celebrations in Northern Ireland when Orange Order marches are at their most fervent.
The potential date clash raises the real prospect of sectarian trouble in Belfast, the Northern Irish capital. Linfield, who have a close association with the Bhoys' arch-rivals Rangers, have prominent Protestant connections while Celtic's deep association with Irish Catholicism is likely to prompt authorities to look into the possibility of moving the date of the fixture, given its combustible timing.
52-time champions Linfield and San Marino minnows SP La Fiorita are to meet in the first qualifying ties on 27/28 June and 4/5 July, after which Celtic will know whether or not a trip to Belfast is on the cards.
Elsewhere in the draw, Welsh side have been paired with Gibraltarian outfit Europa. League of Ireland side Dundalk, who qualified for the group stages of the Europa League last season, take on Norway's Rosenborg.