North Queensland Cowboys and Canberra Raiders must come through elimination matches in order to stay in contention for the NRL title.
Melbourne Storm and Cronulla Sharks moved into the NRL preliminary finals on Saturday, leaving North Queensland Cowboys and Canberra Raiders to face sudden-death showdowns next weekend.
The Storm gained revenge for last season's elimination at the hands of the Cowboys - tries from Suliasi Vunivalu and Jesse Bromwich, together with three penalty goals from Cameron Smith, enough to earn a 16-10 victory over the reigning champions.
Antonio Winterstein and Kyle Feldt went over for North Queensland, but Paul Green's men were never ahead in a tense contest and could have few complaints with the result.
Vunivalu's solo score provided the highlight at AAMI Park, the winger picking up a loose ball before surging through a gap inside his own half and out-pacing Johnathan Thurston to touch down.
The Cowboys will now host Brisbane Broncos in a rematch of last year's title decider, while Melbourne can enjoy a week off ahead of a home preliminary final.
Canberra had won 10 matches in succession to end the regular season, but went down 16-14 to the Sharks courtesy of a late James Maloney penalty, after Elliott Whitehead had needlessly caught Ben Barba with a swinging arm.
Two tries in quick succession from England hooker Josh Hodgson, who was later forced off with a potentially serious ankle injury, and Jordan Rapana put Canberra 12-0 up inside the opening quarter.
However, Matt Prior responded for Cronulla before the interval and the scores were level when Maloney followed up his conversion of a Valentine Holmes try - set up by Luke Lewis' perfectly weighted grubber kick - with a 66th-minute penalty.
Whitehead's illegal hit on Barba then gave Maloney the chance to win the match for a Sharks side missing influential skipper Paul Gallen (back) and the playmaker made no mistake.
The Raiders must now get past the winner of Sunday's match between Penrith Panthers and Canterbury Bulldogs.