Dundalk could face a clash with Welsh club The New Saints in the Champions League third qualifying round should both sides overturn first-leg deficits.
The Airtricity League champions look to have a better chance of progressing after scoring an away goal in a 2-1 defeat by BATE Borisov in Belarus. The Welsh side were beaten 1-0 at home by Hungarian champions Videoton.
Scottish champions Celtic could face a 7,000-mile round trip to Azerbaijan. Ronny Deila's men were paired with either Baku-based Qarabag or Rudar Pljevlja of Montenegro should they maintain their comfortable second qualifying-round lead over Stjarnan.
The teams drew 0-0 in Azerbaijan this week but Qarabag still look likeliest opponents for Celtic given their superior European experience.
Celtic manager Ronny Deila is looking no further than Reykjavik as his side bid to build on their 2-0 first leg lead over Stjarnan, which would have been more emphatic had former Motherwell goalkeeper Gunnar Nielsen not saved a late penalty from Leigh Griffiths.
Celtic were drawn out first for the penultimate round of qualifying, which takes place on 28-29 July and 4-5 August.
Deila, who has taken a strong squad to play Spanish Primera Liga side Eibar on Saturday, told Celtic TV: "That's the next round. Of course we have to get finished with this one and play a good game on Wednesday, and then we can talk about the other teams afterwards if we get a good result."
Dundalk and Celtic both play their second legs next Wednesday.
In the Europa League qualifiers, should Shamrock Rovers progress past Norway's Odds BK they will face more Nordic opponents in the form of either Denmark's Randers FC or Sweden's Elfsborg.
However, Rovers must first overcome a 2-0 home defeat to make that tie a possibility.
UCD would appear to have a better chance of advancing to the third qualifying round. If they overcome their 1-0 defecit to Slovan Bratislava at home in the second leg they'll face FC Krasnodar of Russia in the next round.
If the Premier League's West Ham overcome Birkirkara FC in the second round, they'll go on to face the winners of Inverness Caledonian Thistle versus FC Astra Giurgiu of Romania. West Ham hold a 1-0 lead after the first leg of their clash with Malta's Birkirkara.
The Europa League second round second legs take place next Thursday.
