Saints' winning start to the Gallagher Premiership season went up in smoke as they suffered an infuriating 22-13 defeat at Bath on Saturday afternoon.
Chris Boyd's side enjoyed huge amounts of territory and possession after going 8-0 up thanks to a Rory Hutchinson try and James Grayson's penalty.
But Bath battled for their lives, taking a 10-8 half-time lead, and wing Aled Brew's red card for a forearm smash on George Furbank only served to add fuel to the home fire.
Prop Will Stuart rumbled over to extend Bath's lead and even though Tom Wood responded with a try, Stuart Hooper's side were soon camped in Saints territory again.
Ben Franks and Paul Hill were both sin-binned and a series of scrums, which took eight minutes, allowed Bath to heap misery on Saints.
Zach Mercer eventually scored, and Priestland's conversion ensured Saints would not even take a bonus point from the game as they suffered a fifth successive defeat at The Rec.
It had all started so well as Grayson charged down Priestland's attempted clearance kick and Hutchinson kept his composure, kicking ahead and diving on the ball to score.
Grayson was unable to add the conversion, but Saints remained on the front foot and Freddie Burns was forced to make a big tackle to stop Taqele Naiyaravoro out wide.
Saints had the penalty coming though, and Grayson slotted it to extend his team's advantage.
Semesa Rokoduguni was forced off in another early blow to Bath, but they responded well, upping the tempo and finding the score they craved.
Will Chudley delivered it, sprinting across the face of the Saints defence and arcing his run through a gap before turning on the turbos to score.
Priestland converted and the gap was just one point, but Saints refused to be deterred, with Hutchinson playmaking in typical style as his team tried to find space out wide.
Bath were defending really well, with big hits being made time after time as Saints continued to knock loudly on the door.
But after standing tall, Bath put pressure on at the other end, earning a penalty that allowed Priestland to put them in front.
Saints continued to boss territory and possession though, forcing Bath to scramble on several occasions.
The home side were living dangerously, struggling to get out of their own half and being given the occasional reprieve as the ball just failed to stick for Saints at key times.
And that allowed Bath to go in ahead at half-time as they led 10-8.
Saints had a chance to go back in front early in the second period after winning a scrum penalty, but Grayson missed the central kick from distance.
Bath conceded another kickable penalty soon after, but after Grayson booted it to the corner, they stood tall to win the turnover.
A flashpoint came in the 48th minute of the match as Bath wing Brew was red carded for what referee Ian Tempest saw as a deliberate forearm smash on Saints full-back Furbank.
Furbank went off for a head injury assessment as a result amid a backdrop of boos from the home fans, who were furious at the decision to dismiss Brew.
But it worked in Bath's favour as their fired-up approach paid dividends, with Stuart powering over following a lineout deep in Saints territory.
Priestland missed the conversion as the ball came back off the crossbar, but his side continued to vent their fury in every carry.
Saints won a penalty to relieve some of the pressure and Ahsee Tuala found a gap before knocking on to let Bath off the hook once again.
But Saints finally had their second score when flanker Wood forced his way over the line, rewarding his side for their efforts.
Grayson missed the conversion amid a backdrop of boos from the home fans, leaving Saints two points down with 20 minutes to go.
But the away side's discipline in defence was severely lacking and after Bath booted a penalty to the corner, Franks was sent to the sin bin.
Bath cranked up the heat at the resulting scrum close to Saints' posts, winning penalty after penalty before No.8 Mercer powered over.
Priestland took his full allocation of time before slotting the easy conversion and Saints soon dropped the ball in the Bath half, leading to another scrum and another Bath penalty.
Saints just could not compete up front and Bath kept their foot on the throat of the away team right until the end as they secured their second win in as many league home matches.
Bath: Burns; Rokoduguni (Hamer-Webb 9), Wright, Roberts, Brew; Priestland, Chudley; Obano (Boyce 72), Dunn (Walker 72), Stuart (Judge 72); McNally (Stooke 60), Ewels; Ellis, Bayliss, Mercer.
Saints: Furbank; Collins, Dingwall, Hutchinson, Naiyaravoro (Tuala 60); Grayson, Taylor (J Mitchell 55); Franks (Trinder 74), Haywood (Fish 64), Painter (Hill 64); Ribbans, Moon (Ratuniyarawa 58); Wood (Coles 64), Gibson, Harrison.
Referee: Ian Tempest