They will be joined by Leicester Tigers after they got the better of Midlands rivals Northampton Saints in the night's final game, with Worcester Warriors and Gloucester Rugby having booked their tickets to Bath 24 hours earlier from the opener at Kingsholm.
Hosts Northampton were first up at Franklin's Gardens as they welcomed Newcastle back into the Aviva Premiership fold - the Falcons going on to spoil the party with a 28-22 victory.
Player of the round Tom Catterick and Michael Tait got Newcastle off to a flying start before veteran Saint Paul Diggin pulled one back for his side.
Captain Richard Mayhew then stretched Newcastle's lead further before Saints threatened to snatch victory as Tom Collins scored twice and Harry Betts went over - only for Simon Hammersley to secure a Falcons win at the death.
Next up were Leicester and Sale with the Tigers pipping the Sharks 10-7 thanks to a late Tahir El Mahdi try.
The Sharks had taken the lead through Nathan Fowles only to see Jake Farnworth get Leicester back into the game before El Mahdi wrapped up the late victory whilst Sale's Will Cliff was in the sin-bin.
However Leicester were unable to record back-to-back victories as Newcastle continued their fine return to English rugby's top table with a 19-10 victory.
The Falcons raced into a 19-0 lead thanks to a Harrison Collins double and Catterick try, and although the Tigers clawed their way back into the game with tries from Pasqualle Dunn and Jake Farnworth they left themselves with too much to do.
Next up Sale made up for their earlier late loss to Leicester with one of their own thanks to a 24-22 victory over Northampton.
Sale looked to by flying thanks to a John O'Donnell double only for Diggin, captain Ryan Glynn and another Tom Collins double to see Saints leading late on.
But the home side couldn't hold on as Nathan Fowles and Josh Fowles went over to hand Sale their first victory of the evening.
In the next clash Newcastle made it a clean sweep with a 12-5 victory over Sale Sharks, tries from Joel Hodgson and captain Mayhew doing the damage, Tom Brady touching down in reply.
In a repeat of last year's Aviva Premiership final Northampton and Leicester faced off in a winner-takes-all tussle in the night's final game with the victor moving on to Bath for the Series Finals.
And it was once again Leicester left celebrating as they won 17-5, an El Mahdi double and a try from David Williams cancelling out an Alex Day score for Saints