Derek McInnes’ Aberdeen could face AEK Larnaca or KAA Gent for a place in the Europa League group stages.
The Dons were unseeded for the draw for the play-off round, which was made in Nyon, Switzerland today.
Aberdeen, who defeated Georgian side Chikhura Sachkhere 6-1 on aggregate in the second qualifying round, take on HNK Rijeka with the first leg in Croatia on Thursday.
The winners will advance to take on either Cypriot side AEK Larnaca or KAA Gent from Belgium with the matches taking place on August 22 and 29.
The Dons have never made it past the third qualifying round during McInnes’ time at Pittodrie.