Celtic have been drawn against Kazakhstan champions Shakhter Karagandy, the lowest ranked club remaining the Champions League, in the play-off round - arguably the best draw they could have hoped for. Shakhter Karagandy have a worse UEFA club coefficient than Sligo Rovers, however they have already knocked out Belorussian champions BATE Borisov, who currently have a higher UEFA coefficient than Celtic, so it may not be as easy as it looks...
Arsenal got Fenerbache which might be tricky, but Arsenal are by far the highest ranked team yet to qualify and I can't see them failing to get through to the group stage from here.