Rob Horne will make his Saints debut against Leicester Tigers at Franklin's Gardens on Saturday (kick-off 4.30pm).
Horne, who scored during an impressive 40 minutes for the Wanderers at Sale Jets on Monday night, lines up at 13, alongside Luther Burrell.
George North, another man who was on Wanderers duty earlier in the week, also gets a place in the first 15 as he takes the No.14 shirt.
There are no further changes to the back line that started last Saturday's 55-24 defeat to Saracens, with Tom Collins fit enough to start on the other wing.
South Africa scrum-half Cobus Reinach will hope to make his Saints bow from the bench.
In the pack, Courtney Lawes moves to six with Tom Wood missing out after taking a bang to the shoulder in training.
Lawes is part of a whole new back row, with Jamie Gibson replacing Lewis Ludlam at seven and Teimana Harrison coming in for ankle sprain victim Mitch Eadie.
Michael Paterson takes Lawes' place in the second row.
Leicester, who lost 27-23 at home to Bath last Sunday, have been forced to make a change at centre, with the injured Manu Tuilagi replaced by Matt Smith.
Dan Cole comes in at tighthead, with Logovi'i Mulipola dropping to the bench.
Saints: Tuala; North, Horne, Burrell, Collins; Mallinder, Groom; Waller, Hartley (c), Brookes; Paterson, Day; Lawes, Gibson, Harrison.
Replacements: Haywood, Ma'afu, Hill, Ratuniyarawa, Ludlam, Reinach, Grayson, Foden.
Leicester Tigers: Veainu; Malouf, Smith, Toomua, May; Ford, B Youngs; Genge, T Youngs (c), Cole; Barrow, Kitchener; Hamilton, O'Connor, Kalamafoni.
Replacements: Thacker, Bateman, Mulipola, Williams, Ryan, Harrison, Ford, Tait.