With not too much separating the two teams and given that both clubs were once part of the same league competition, there is every chance we will see a very interesting affair at Ljudski Vrt in Maribor.
Maribor have been dominating Slovenian football over the last few years and they won the league title in style, finishing 20 points above second-placed Olimpija.
Boss Darko Milanic managed to keep most of the squad together, with striker Dalibor Volas the only high-profile player who left the club this summer.
Forward Etjen Velikonja has already agreed a switch to Cardiff, but he will help his side in the Champions League clash with Zeljeznicar.
Having shown a lot of potential in friendly games against Metalist Kharkiv and Lokomotiv Moscow, Maribor look a good bet at 1.53 (8/15) offered by Stan James.
Besides the home field advantage that will not be so great because of the number of Bosnians in Slovenia, the hosts can take heart from the fact their domestic season has already started, as the Purples beat Olimpija to the Super Cup trophy before defeating Gorica in the league.
Apart from Mitja Viler, boss Darko Milanic will have fully fit squad to choose from for the first leg against Zeljeznicar.
Probable starting line-up (4-4-2): Handanovic – Mejac, Rajcevic, Potokar, Trajkovski – Mezga, Lesjak, Filipovic, Ibraimi – Tavares, Velikonja.
Just like their next rivals, Zeljeznicar have been extremely dominant on the domestic stage of late, although they finished the league campaign eight points clear of the second-placed Zrinjski.
However, the 34-match unbeaten run that came to an end in the final round of the season proved the Blues are becoming a real force to be reckoned with, and they now need to prove their worth in Europe as well.
The club enter the new season with virtually unchanged squad, although defender Patrick Gerhard Nyema has left the club and keeper Marjan Antolovic arrived on loan from Legia Warsaw.
Striker Danijal Brkovic also joined from Velez, but he is seen as one for the future even if he will be in contention for the Maribor game.
Zeljeznicar were quite convincing in pre-season, beating the likes of Pecsi and Mattersburg, while sharing spoils with Kryvbas and Gloria Bistrita, although they did lose to Sigma Olomuc.
Boss Amar Osim has absolutely no selection worries before the trip to Slovenia, but Zeljo could still be in for a difficult task at Ljudski Vrt.
Probable starting line-up (4-3-3): Antolovic – Colic, Bogicevic, Kerla, Kvesic – Svraka, Jamak, Bekric – Selimovic, Adilovic, Zeba.