Woodville ended Adelaide University's finals hopes while Old Collegians put Souths' dream in dire straits during Round 14.
Stung by a four-point loss to Barossa last week that left them out of the finals frame, Wasps ensured Uni would share their pain with an eight-point win at Gleneagles Reserve.
The students fought hard with Mark Ross' double a highlight but the hosts wouldn't be denied, running out 32-24 victors to leave Uni stranded in seventh, 14 competition points behind fourth-placed Barossa with two games in hand.
The Rams enjoyed a percentage-boosting 98-0 win over Port Adelaide to tighten their grip on a finals berth but have Old Collegians to thank after their 42-36 win over Southern Suburbs.
Old Colls left it late against Souths with two-try hero Nicholas Howlett and Keshawa Randil crossing in the final minutes to secure a dramatic six-point win on the road.
Two Sesoni Rokotuiloma penalty goals ultimately proved the difference as the sides scored six tries and three conversions apiece.
The result leaves Souths in fifth place and needing at least one win from their upcoming fortnight against Woodville (home) and Brighton (away) to scrape into finals.
Meanwhile Brighton and Burnside are destined to meet in yet another qualifying final after banking maximum points against Elizabeth and Onkaparinga respectively.
Burnside's 49-7 defeat of Onkas ended the Devils' own playoff hopes with Max Hodell's double sparking a late surge at Wilfred Taylor Reserve.
However, the Double Blues didn't have it all their way with Grace Fitzsimmons, Ashley John and Jade Pilkington sparking a 17-14 upset over that secured Onkas' place in the women's finals.
They'll face Burnside again in two weeks time after Woodville and Souths extended their lead atop the ladder with bonus point wins over Uni and Port Collegians last weekend.
