Courtney Lawes and Salesi Ma’afu both miss Saints’ Aviva Premiership trip to Exeter Chiefs on Sunday.
Lawes suffered a shoulder problem in last Saturday’s defeat at Clermont Auvergne and was withdrawn at half-time.
The lock is replaced by Christian Day, who played the second half at Stade Marcel Michelin, while Ma’afu’s place is taken by Gareth Denman, with Tom Mercey on the bench.
The only other change comes at scrum-half, where Kahn Fotuali’i replaces Lee Dickson as the pair continue to rotate.
England prop Alex Corbisiero is fit enough to start after taking a bang to the knee in last weekend’s 37-5 Champions Cup loss.
Meanwhile, Exeter are boosted by the return of Phil Dollman and Jack Nowell, with the England man starting at centre.
The Chiefs name an unchanged pack from the one which demolished Newcastle Falcons in the Amlin Challenge Cup last weekend.
Moray Low’s hamstring injury means Alex Brown is the tighthead option on the bench, while there is a first-ever inclusion in the top flight for highly-rated Academy youngster Sam Skinner.
Exeter Chiefs: Whitten, Nowell, Hill, Jess; Slade, Chudley; Moon, Yeandle, Francis; Mumm (c), Lees; Ewers, White, Waldrom.
Replacements: Taione, Rimmer, Brown, Skinner, Horstmann, Lewis, Steenson, James.
Saints: Wilson; K Pisi, G Pisi, Burrell, Elliott; Myler, Fotuali’i; Corbisiero, Hartley (c), Denman; Manoa, Day; Wood, Clark, Dickinson.
Replacements: Haywood, A Waller, Mercey, Fisher, Dowson, Dickson, Stephenson, Tuala.