Skipper Hartley ruled out of Saints' battle with Bath
Dylan Hartley will miss Saints' clash with Bath at Franklin's Gardens on Friday night due to a hand injury.
Tom Wood is also absent as he continues to nurse the shoulder problem that ruled him out of last Saturday's 24-11 victory against Leicester Tigers at the Gardens.
But both players are expected to return to training next week, with Stephen Myler (knee) and Piers Francis (jaw) also making good progress.
Saints make three changes to the team to face Bath, with Mike Haywood, Paul Hill and David Ribbans replacing Hartley, Kieran Brookes and Christian Day.
George North is passed fit to start on the wing after the Wales star was forced off against Tigers last Saturday.
Courtney Lawes will captain Saints from the back row.
Bath are able to call on former Saints scrum-half Kahn Fotuali'i, who starts in the nine shirt for the west country outfit on Friday night.
Full-back Anthony Watson is fit enough to play after taking a bang to the shoulder in his team's 31-21 success against Saracens at The Rec last Saturday.
Flanker Sam Underhill will make his first Bath start after joining the club from Ospreys during the summer.
Saints: Tuala; North, Horne, Burrell, Collins; Mallinder, Groom; Waller, Haywood, Hill; Paterson, Ribbans; Lawes (c), Gibson, Harrison.
Replacements: Marshall, Ma'afu, Brookes, Day, Ludlam, Reinach, Grayson, Foden.
Bath: Watson; Rokoduguni, Joseph, Tapuai, Banahan; Priestland, Fotuali'i; Obano, Dunn, Perenise; Ewels, Stooke; Garvey (c), Underhill, Faletau.
Replacements: Walker, Auterac, Andrews, Phillips, Grant, Allinson, Burns, Clark.