Just looked at the various leagues and when they enter, these are our potential opponents based on current standings:
Possibly a winner from the second round: Sturm Graz, Fenerbahce, Midjtylland, APOEL (Dynamo Kyiv are seeded here so we wouldn't face them, unsure on the others)
Third round: Benfica (surely to god seeded), Rennes, PSV, Club Brugge.
Bert Kassies will be much clearer than me just browsing Wikipedia in terms of who's going to be seeded, and obviously league places can change, but I don't fear anyone there. Benfica/PSV would be big tests but nothing beyond our ability.
EDIT: The entry here will be out of date but aye, those are the kind of teams we're looking at.