Bath boss Stuart Hooper saluted his side for way they 'suffocated and squeezed' Saints in Saturday's game at The Rec.
Hooper's side shrugged off wing Aled Brew's 48th-minute dismissal as they marched to an impressive 22-13 Gallagher Premiership success.
Saints, who went into the game sitting top of the league table, had led 8-0 inside the opening 10 minutes thanks to Rory Hutchinson's try and James Grayson's penalty.
But Bath bounced back thanks to Will Chudley's try and the boot of Rhys Priestland, leading 10-8 at half-time.
Brew was then sent off for a forearm smash on George Furbank, but Bath scored twice more after cranking up the heat in the forward battle.
And Hooper said: "That's rugby: the emotional side of it and the team wins on days like that.
"The guys go out there for each other and that allowed them to be successful.
"Scrum and lineout has been consistent, something we've put a huge emphasis on right from the beginning.
"We understand our game needs to grow and develop and we need to make use of our attacking players in the backs, but afternoons like that you need the ability to keep it tight in the forwards and we did.
"We worked hard on the scrum during the week and it was part of the plan because we understood it was our way into the game.
"Northampton obviously came here top of the tree and having scored 13 tries so we knew we needed to suffocate and squeeze them.
"Credit to the players, their application to the detail out there was unbelievable."