Northampton maintained their recent dominance over Bath after fly-half JJ Hanrahan's late penalty shaded a dour Recreation Ground contest.
Hanrahan's 72nd-minute strike edged Saints home 13-11, and made it 10 games unbeaten against the west country club in all competitions.
Wing Semesa Rokoduguni looked to have condemned Northampton to a fourth Aviva Premiership defeat of the season after his classy second-half try put Bath in front, but Hanrahan had other ideas.
Rokoduguni's touchdown followed two George Ford penalties after Northampton led through centre Luther Burrell's try when he intercepted a Ford pass, while Hanrahan landed an earlier penalty and conversion.
Bath made a late change when their England lock Dave Attwood was ruled out and replaced by Charlie Ewels, while Ross Batty withdrew from bench duty, with Tom Dunn taking over as reserve hooker.
Northampton, meanwhile, arrived in the west country without injured England forwards Tom Wood, Courtney Lawes and Dylan Hartley as they targeted a first Premiership away win since February, which also came against Bath.
Referee Craig Maxwell-Keys proved the dominant figure during a forgettable opening quarter that ended scoreless and was notable only for eight scrummaging re-sets.
As a result, there was no fluency or pattern to the game, with Bath conceding six successive penalties and Hanrahan opening Northampton's account through an angled 24th-minute strike.
Bath could make little headway, and Northampton, playing with the wind against them, were content to go through the phases, make small territorial gains and keep their opponents away from the danger zone.
The home side's frustration was then underlined five minutes before half-time when their England international prop Henry Thomas was sin-binned following yet another scrum, and Northampton were content to troop off at half-time with a 3-0 advantage.
Bath, though, needed less than three minutes of the second period to open their account, with Ford kicking an equalising penalty after Saints lock Christian Day infringed at a ruck.
Scotland international David Denton appeared off the bench for his home debut after 46 minutes, briefly replacing Matt Garvey before Garvey rejoined the action, but Bath then fell behind for a second time when Northampton were gifted a try.
Ford appeared to be caught in two minds inside his own 22 whether to kick or pass, and when he chose the latter option, Burrell gratefully stole possession and crossed unopposed between the posts for a try that Hanrahan converted.
A second Ford penalty four minutes later cut the gap to 10-6, and Denton was then sent on as a permanent substitute, replacing number eight Leroy Houston, but Bath blew a gilt-edged scoring opportunity when they lost possession as Saints' line beckoned.
They kept plugging away, though, and went ahead 17 minutes from time when Rokoduguni cruised past Saints full-back Ben Foden and then avoided George North's attempted tackle for a try that inched Bath in front.
But they could not keep their discipline, and Irishman Hanrahan stepped up to settle the game, meaning that Bath will return to European Champions Cup action next weekend after losing four out of six Premiership games this term.