Zabreg cancelled out Maribor's away goal after just 12 minutes.
Centre-back Tonel was on hand to fire home from six yards out after a corner fell to him in the box.
Maribor responded well to going behind. Zeljko Filipovic drifted in off the right wing to test the goalkeeper from 35 yards.
Then just before half-time Agim Ibraimi saw his shot blocked after he cut inside from the left-hand side.
The away side decided to rest a couple of players at half-time, with Jerko Leko replacing Fatos Beqiraj and Adrian Calello on for Arijan Ademi.
With five minutes to go, Maribor's frustration showed when Soares Arghus was sent off for a bad tackle.
The Croatian side saw the game out and will be awaiting next Thursday's draw for the group stage.