Fa’atoina Autagavaia will make his first Saints start in Friday night’s Heineken Cup clash with Castres at Franklin’s Gardens (kick-off 7.45pm).
The Samoan full-back, who arrived at Northampton as injury dispensation for Ben Foden last month, comes in for Tom Collins, who took a knock to his shoulder in last Sunday’s win at Ospreys.
Autagavaia came on for Collins at half-time in the 29-17 success at the Liberty Stadium, making his second appearance for his new club after coming off the bench against Harlequins on January 3.
Lee Dickson also comes into the Saints side for the visit of the Top 14 champions, with Kahn Fotuali’i named among the replacements.
Tom Wood has shaken off the knee injury that saw him leave the field seven minutes before the end at Ospreys and Ken Pisi returns from a hamstring injury to take his place on the bench.
Saints can still qualify for the Heineken Cup quarter-finals, but will need to win and hope other results go their way.
Saints: Autagavaia; Elliott, G Pisi, Burrell, North; Myler, L Dickson; A Waller, Hartley (c), Ma’afu, Lawes, Day, Clark, Wood, Manoa.
Replacements: Haywood, E Waller, Denman, Dowson, Dickinson, Fotuali’i, G Dickson, K Pisi.
Castres: Dulin; Garvey, Cabannes (c), Lamerat, Grosso; Kirkpatrick, Tomas; Forestier, Rallier, Peikrishvili, Samson, Gray, Babillot, Bornman, Faasalele.
Replacements: Taumopeau, Coetzee, Lazar, Desroche, Caballero, Kockott, Bonnefond, Lakafia.