Widnes suffered relegation after seven years in Super League as they suffered a 20-12 defeat to Toronto Wolfpack.
Two more Championship sides, Toulouse, who beat Hull KR 34-23, and London Broncos, who beat Salford 11-8, also won against Super League opposition.
It means the make-up of the top tier in 2019 is still to be decided going into the last weekend of the season.
On Sunday, 2017 Super League champions Leeds can ensure survival by winning at Halifax, bottom club in The Qualifiers.
But there are still a lot of gaps to fill over the course of four days next week - with just two points separating all top six clubs.
Even before the Million Pound Game on Saturday 7 October between the two sides finishing fourth and fifth, none of the eight teams in The Qualifiers have yet ensured a top-three finish to secure a place in Super League for next season.
Salford host Toulouse on Thursday, while Toronto, who finished eight points clear in the Championship, will play Leeds at Headingley on Friday.
Broncos then meet Halifax on Saturday before Hull KR are at home to Widnes next Sunday (30 September, 15:00 BST).
Nightmare run for the Vikings
After finishing bottom of the table in the 23-match regular season, Widnes had another chance to survive via the Qualifiers.
Last weekend they at least ended a winless run going back to 22 March when they beat Halifax, who were bottom of The Qualifiers and already fated to spend another season in the Championship.
But the end finally came for Widnes at the Lamport Stadium in Ontario as Toronto scored three tries though Cory Paterson, Matty Russell and Blake Wallace, while Joe Mellor and Chris Dean replied for the Vikings.
Widnes chief executive James Rule put out a statement in the wake of his side's relegation, calling it "a devastating moment for everyone associated with the club".
He added: "We simply wish to apologise for the experiences of the past two seasons. Results have fallen far below our expectations and provide assurances on future ambitions.
"The Vikings intend to remain a professional, full-time organisation. We are determined to make every effort to retain the best of our talent, and to also effectively rebuild this squad, with the intention of making an immediate return to the Super League."
The key remaining dates
- Thursday 27 September: Salford v Toulouse (19:45 BST)
- Friday 28 September: Leeds v Toronto (19:45 BST)
- Saturday 29 September: London Broncos v Halifax (19:05 BST)
- Sunday 30 September: Hull KR v Widnes (15:00 BST)
Turnaround in Toulouse
Toulouse kept alive their promotion hopes as they recovered from an early 19-0 deficit to score six tries against Hull KR in front of a 4,127 crowd at Stade Ernest Argeles.
The game was turned on its head when Toulouse touched down three times in six minutes just before half-time.
Second rower Rhys Curran, centre Chris Centrone and half-back Stan Robin all went over for tries which were converted by Mark Kheirrallah to bring his side to within a point at 19-18.
Toulouse then went in front for the first time two minutes after the restart courtesy of a penalty from Kheirallah, before Gavin Marguerite went over for another try and Centrone added his second score to extend the lead to 28-19.
Kheirallah kept the scoreboard ticking over with a penalty before Bastien Ader rounded off his side's scoring on 65 minutes.
Craig Hall grabbed his second try of the night, his 13th in seven matches since returning to the club, eight minutes from the end but the visitors had left themselves with too much to do.
London Broncos beat Salford thanks to their best defensive display of the season when they needed it most, according to coach Danny Ward.
The 11-8 victory keeps the Broncos in the hunt for a place in the Million Pound Game.
Jarrod Sammut had opened the scoring for the Broncos with an early penalty, before Jay Pitts crossed for the first try as he filled in at standoff to compensate for the home side's injury problems.
The conversion and a drop-goal from Sammut stretched the Broncos' lead to nine points before Salford hit back through Greg Johnson, but another Sammut penalty effectively made the game safe despite Johnson's second try.
Following successive defeats, Salford now need to beat Toulouse on Thursday to secure their Super League status.