It is west of Zagreb , between the eastern slopes of Samoborsko gorje ( Samobor hills , the eastern part of the Å 1\/2 umberak Mountains ) , in the Sava river valley . Samobor is located west of Zagreb , between the eastern slopes of the Samoborsko gorje ( , the eastern part of the Å 1\/2 umberak Mountain ) , in the Sava River valley .