Bager completed a remarkable fight back for the Bankwest Women?s State Premier League champions, who had trailed to Daniela Di Bartolo?s double midway through the first half.
Goals from Aleisha Dyer and Ellie Blackmore brought the Redbacks level at 2-2 and the teams could not be separated during a tense extra-time. But the visitors made the most of their opportunities in the shoot-out to seal a remarkable victory.
In the Amateur Men?s Interstate Club Challenge, North Perth United found themselves in a similar predicament to the Redbacks when Sam Bueti scored twice for Inter with just 25 minutes gone.
But just as their female counterparts had rallied against Adelaide City, North Perth United fought back and were level at the break through goals from Nicola Pozzobon and captain Patrick Montgomery.
Christian Cella scored from the penalty spot to put Inter ahead again before Pozzobon scored his second for North Perth.
The home side seized control of the match in the latter stages and goals from Matthew Bueti and Matthew Weistra sealed a 5-3 win.
The match between respective State League champions Bayswater City and Campbelltown City is expected to be rescheduled for early next year.
Northern Redbacks: Renee Leota; Katie Moth; Aleisha Dyer; Jacqueline Nellany; Lauren Riley; Charlotte Farrell; Nicola Williams; Larissa Walsh; Rita Mankowska; Carla Bennett (c); Clare Dunn; Kathleen Waycott; Emily Dunn; Ashlee Bager; Eleanor Blackmore; Haylee Richards. Coach: Neil Bennett. Team officials: Jessica Nuess; Dave Whiteside; Tim Hodgson.
North Perth United: Rorie Cowan; Kevin Flavin; Clayton Stone; Mark Curran; Gregg O?Flanagan; Ryan Fitzgerald; Aaron O?Neill; Davy Lyttleton; Richard Dendle; Nicola Pozzobon; Steven McGrath; Patrick Montgomery (c); Darragh Cullen; Keith Donegan; Adrian Rockett; Scott Stephens. Coach: Alex Carter. Team officials: Mark Rockett; Mark Reid; Paul Reid.