The Barbarians beat competition leaders Pirates Old Boys 29-25 in Te Anau, while Marist had a 29-24 win on their home ground against Blues.
Woodlands had already booked a home semifinal before beating Star 56-22 on Wednesday night.
Woodlands had lost their previous three games but with Marty McKenzie slotting in at first five in the rare midweek game, they bounced back in style to knock the defending champions out of finals contention.
Second five Fletcher Morgan scored four of Woodlands’ eight tries and landed all eight conversions. Morgan has been one of the competition’s best players this season.
The Barbarians scored a try in the last play of the game to claim victory over POB.
The Barbarians had dominated the opening 20 minutes in Te Anau and scored the first two tries.
During the 10 minutes before halftime, POB front-rowers Alex Fraito and Levi Gage barged over for tries. The Barbarian forwards then scored from a lineout drive on the stroke of halftime to lead 19-12.
Fraito scored again in the second half and a couple of penalty goals to Kaea Nikora had the visitors ahead 25-22 with 10 minutes to go.
The Barbarians scored in the last play of the game to secure the five competition points.
The Baabaas will determine whether they finish third or fourth after their 13th and last game this Saturday against Star.
Marist earned a 29-24 over Blues on a heavy surface at Miller Street.
Blues started the game well and led 24-12 at halftime.
Halfback Connor McLeod and Stags team-mate Faletoi Peni, at second five, took the field in the second half.
Marist coach Derek Manson said the two Stags had been a welcome addition in recent weeks, but the whole team were improving.
"Our fullback, Aiden Harrington, was out with a broken thumb for the first half of the season but he’s been very good for us in recent weeks,’’ Manson said.
‘‘Xavier Wright is going good on the blindside. He’d been coming off the bench for first half of the season but he has been nailing the starting role."
Manson said the coaching team were happy with how their team ground out a victory on Saturday.
"It wasn’t pretty but the boys had belief and knew how to win. They (Blues) made us work hard for it."
Marist No 8 Ben Fotheringham was man of the match. Marist scored five tries to three, backline players Keanu Kahukura and Riley Hika scoring two tries each in the second half.
By John Langford
