Four straight wins have rocketed Corrimal into the top four but to stay there they'll likely need to beat Keira at Ziems Park on Saturday.
Last Saturday's washout of day one of round 12 leaves the round to be played as modified one-dayers.
Only unbeaten leaders Balgownie and second-placed Keira are assured of a finals spot, with just seven points separating fourth-placed Cougars from seventh-placed Northern Districts.
Corrimal leapfrogged University into fourth spot with victory over the Students in round 11.
Cougars skipper Rob Fisher led the way with 92, while six bowlers took a wicket in a 44-run win.
But with just two rounds before the finals Corrimal know their spot in the top four may be only a short one if they can't beat Keira.
The Lions will be desperate to claim a top two finish and rain insurance for the semi-finals and found form with a thumping win over Port Kembla in round 11.
A weakened Port were dismissed for just 79, with Keira reaching the target with more than 31 overs to spare.
Meanwhile, Helensburgh premiership defence is hanging by a thread with the Burgh facing a must-win clash at home to third-placed Dapto.
The Burgh are coming off a loss to Wollongong, while Dapto outclassed Wests Illawarra.
A victory for Dapto would seal a semi-final spot and they are still challenging Keira - who they meet in the final round - for a vital top two spot.
In other games, unbeaten Balgownie can seal the minor premiership with a win over Port Kembla.
Fifth-placed University will be looking to keep their semi-final hopes alive with a win over Northern Districts at Uni Oval.
Wests are without a win this season and take on the inconsistent Wollongong.
Ladder: Balgownie 77, Keira 65, Dapto 56, Corrimal 48, University 44, Helensburgh 42, Northern Districts 41, Wollongong 36, Port Kembla 33, Wests Illawarra 11.
University v Northern Districts at Uni Oval
Wests Illawarra v Wollongong at Figtree Oval
Corrimal v Keira at Ziems Park
Helensburgh v Dapto at Helensburgh Oval
Balgownie v Port Kembla at Judy Masters Oval