Leeds Carnegie were left facing a third relegation in six seasons after a heartbreaking 31-24 defeat to Northampton.
Neil Back's men produced an outstanding first-half performance to lead 24-15 at the break against the understrength Saints, who booked their place in the play-offs.
Yet they failed to register any points after the break as Northampton wore them down to secure a fourth-placed finish to leave Leeds facing a nervous wait on their future. If Worcester win the two-legged Championship play-off against Cornish Pirates, then Leeds will be relegated as only Warriors meet Premiership entry criteria.
Leeds could hardly have made a better start as England flanker Hendre Fourie crossed the line in the fourth minute. Fly-half Adrian Jarvis added the extras and four minutes later it got even better as Rhys Oakley touched down and Jarvis again proved reliable with the boot.
At 14-0 up after just eight minutes, Leeds were on course for a stunning victory. Northampton fly-half Shane Geraghty got Saints off the mark in the 12th minute with a penalty but the influential Jarvis, who proved an assured presence for the visitors at fly-half, replied with one of his own for Leeds soon after. And in the 18th minute Leeds were in dreamland when wing Peter Wackett crossed the line for a try which Jarvis again converted.
Leeds wing Lee Blackett and Northampton wideman Paul Diggin were sin-binned and in the 29th minute Northampton touched down through Phil Dowson. Geraghty missed the conversion but Leeds then lost forward Juan Gomez to the sinbin. Two minutes before the break, Saints were awarded a penalty try which Geraghty converted.
Seven minutes after the restart, England wing Chris Ashton powered over for Saints and Geraghty again converted before Stephen Myler added three penalties to break Leeds hearts.
Tries: Dowson, penalty try, Ashton,
Cons: Geraghty 2
Pens: Geraghty, Myler 3
For Leeds Carnegie:
Tries: Fourie, Oakley, Wackett,
Cons: Jarvis 3
Yellow cards: Diggin (Northampton - 27th min); Gomez (Leeds -27th min); Blackett (Leeds -37th min)
Northampton: 15 Ben Foden, 14 Chris Ashton, 13 Joe Ansbro, 12 James Downey, 11 Paul Diggin, 10 Shane Geraghty, 9 Stuart Commins, 8 Roger Wilson, 7 Phil Dowson (capt), 6 Mark Easter, 5 Christian Day, 4 Mark Sorenson, 3 Brian Mujati, 2 Brett Sharman, 1 Alex Waller.
Replacements: 16 Dylan Hartley, 17 Soane Tonga'uiha, 18 Tom Mercey, 19 Courtney Lawes, 20 Calum Clark, 21 Lee Dickson, 22 Stephen Myler, 23 Bruce Reihana.
Leeds Carnegie: 15 Michael Stephenson, 14 Lee Blackett, 13 Henry Fa'afili, 12 Scott Barrow, 11 Peter Wackett, 10 Adrian Jarvis, 9 Scott Mathie, 8 Alfie To'oala, 7 Hendre Fourie, 6 Rhys Oakley, 5 Kearnan Myall, 4 Daniel Browne, 3 Juan Gomez, 2 Steve Thompson, 1 Mike MacDonald.
Replacements: 16 Phil Nilsen, 17 Gareth Hardy, 18 Gareth Denman, 19 Phil Swainston, 20 Tom Denton, 21 Dan White, 22 Christian Lewis-Pratt, 23 Uche Oduoza.