Sheffield Eagles had their nerves shredded before becoming the last team to book their place in next month's Championship play-offs.
Sheffield twice had to come from behind to beat Leigh 29-28 at Bramall Lane.
Leigh led with first-half tries from Mick Nanyn and Lee Mitchell, but Misi Taulapapa's hat-trick and a Tim Bergin try earned a 22-10 home interval lead.
The visitors hit back to level, but Craig Cook's try was converted by Simon Brown, whose late drop goal sealed it.
Ricky Bibey then managed another last-gasp try for the visitors, but it was too late to deny Sheffield sixth place.
Leigh's other tries came from John Duffy and a second for Nanyn, who kicked four goals.
The Centurions' bonus point from Thursday night's defeat seals third spot to earn them a rematch against Sheffield in the first preliminary semi-final, at Leigh Sports Village.
Widnes booked their place in the Championship play-offs as they ensured that they would finish fifth with Wednesday night's 32-14 win at fourth-placed Barrow.
And they too will now face each other again in the preliminary semi-finals, at Craven Park.
Richard Varkulis ran in a hat-trick for the Vikings, two of his three tries coming before the break, to follow one from Kurt Haggerty, as Widnes went in 16-0 up.
Anthony Thackeray and centre Varkulis added two more tries to make it 26-0.
Preliminary semi-finals: Leigh v Sheffield Eagles, Barrow v Widnes (losers eliminated).
Featherstone v Halifax (winners through to Grand Final, losers to major semi-final).
Managerless Barrow finally responded with three of their own through Andy Ballard (2) and Jamie Rooney.
But winger Paddy Flynn got in on the try-scoring act for Widnes to seal a timely third successive victory for the Vikings.
Toulouse, who finish their season at home to Halifax on Saturday evening (1900 BST), have extended deals for Sebastian Planas and Constant Villegas by a further year.
Martin Mitchell (ankle) is out, while Cedric Gay and Vincent Duport both face fitness tests.
Sam Barlow (suspension) is missing for Halifax, but coach Matt Calland is hopeful that Said Tamghart can return to action.
In Sunday's games, Iain Morrison (knee) is the only Featherstone Rovers absentee for their final league fixture at home to Barrow, stand-off Kyle Briggs having recovered from a hip injury.
Barrow have to bounce back from a double blow, Steve McCormack having resigned as head coach on Tuesday, before Widnes beat the Raiders 32-14 on Wednesday night to end their hopes of a top three finish.
Barrow pair Richard Fletcher and Chris Young face late fitness tests.
Keighley aim to go out with a bang as they prepare for the final Championship fixture of the season at home to Widnes.
"It's been a tough season, and we're mentally drained because of the emotions we've gone through," said coach Barry Eaton. "But we've had a really good chat about it, and we're pretty confident we can raise ourselves for one last game."
Eaton has been successful in agreeing new contracts with Dan Belcher, who is out with a shoulder injury, Will Cartledge and James Hutchinson for next season.
Whitehaven legend David Seeds looks set to take charge of Sunday's clash withBatley following the sacking of Ged Stokes.
Batley's Tommy Gallagher (knee) is missing for Karl Harrison's men, although Mick Govin could return from an ankle injury.
The Northern Rail Cup winners now have nothing to play for following Sheffield's win against Leigh on Thursday night.
Hunslet Hawks coach Paul March has urged his title-winning team to finish the year with a flourish.
The Hawks, three points clear of Oldham, are assured of top spot going into their final game against South Wales Scorpions, due to a vastly superior points difference.
But March said: "We haven't gone all this way just to win it on points difference or a bonus point. We want to be clear at the top and the lads are looking forward to it.
"From 1999, when Hunslet got told they wouldn't be going up to Super League, some supporters took their bat home while others carried on supporting the club.
"They've been through thick and thin, and this season is for them really. It's all about the club."
Richard Chapman and Charlie Wabo are suspended. But March said: "We've players who can come in to fill those gaps."
South Wales Scorpions coach Anthony Seibold said: "Hunslet have been by far the best team this year and their consistency has been rewarded. They have threats all over the park including the March brothers, Tommy Haughey, Wayne Price and Wayne McHugh.
"They are a big strong team who play very well off the back of their offloads. They taught us a lesson when they played us on Easter Monday.
"We will need to be at our very best if we are to get something."
Workington Town coach Gary Charlton hopes John Lebbon, Joe McKenna, Stewart Rhodes and Jason Mossop could all return to action for the trip toDoncaster.
Workington are not yet mathematically sure of a place in the play-offs, but only a freak set of final-day results can deny them.
Swinton Lions need a big win against bottom club Gateshead Thunder to be coupled with Doncaster beating Workington if they are to have any chance of making the play-offs.
Phil Wood returns forRochdale Hornets at home to Blackpool Panthers, who could be without Paul Alcock.