The first leg of these two ties, which must be negotiated to ensure progress to the group stages, takes place on August 18.
With Craig Bellamy ruling himself out of a move back to Parkhead – even on loan – Knowledge Musona off to Hoffenheim, and trialists Stipe Pletikosa, Stijn Stijnen, Katlego Mphela and Milos Lacny all failing to do enough to be offered contracts, Neil Lennon is now focusing on the other options.
Among them are Newcastle keeper Fraser Forster and Polish shot stopper Grzegorz Sandomierski.
Parkhead keeper coach Stevie Woods is reported to have travelled to watch the 22-year-old play for his club, Jagiellonia Bialy- stok, this week.
Originally, Lennon wanted to see the man who has already broken through to the Polish national team spend a few days at Lennoxtown.
But Sandiomerski's club are not keen on allowing the keeper they rate at around £2million to do this and requested that Celtic agree a transfer fee before they would allow him to come across to Scotland.
Lennon at least knows all about the qualities and character of Forster, who spent last season on loan at Celtic where he helped set a new shut-out record for the club.
The manager believes he only needs one or two more players, but would prefer to get them aboard before the signing deadline for participation in the play-off round for the Europa League.
If they can get through this knockout round – the draw for which is made on Friday – there is another signing deadline at the end of this month for the Group Stage.
Lennon will use tonight's final warm-up game here in Swansea to take a look at some of the men on the fringes of his squad, and a few could be pulling on a Hoops shirt for the final time.
Having used most of his players over the past week in the games against Wolves, Inter Milan and an Airtricity XI, Lennon will use a mixture of first-choice and back-up men against the newly-promoted Welsh club at the Liberty Stadium.
He said: "We will try and put a good team out. Again, we might look at a different formation and see how that suits some of the players.
"We will go with a strongish team, and we'll leave some of the more senior boys who put a lot of effort in over the weekend behind just so they have a couple of training days ahead of our SPL game against Aberdeen at Pittodrie on Sunday."
Daryl Murphy – who scored from the spot at the Aviva Stadium on Sunday against Airtricity – could be back in the shop window tonight.
He is already attracting interest from England, with Wolves the latest club linked with the Republic of Ireland striker.
But Lennon would like to get another attacking player on board before he sanctions any departures.