Saints boss Gus MacPherson kept faith with the same team that beat Dundee United last week, while Motherwell had to make changes after their red card mayehm against Dunfermline on Monday night.
The first half was fairly poor affair, with both teams offering very little. It will be forgotten pretty quickly Saints best chance came when Stewart Kean shot just wide from a difficult angle.
Seven minutes from the break, the home side took the lead when a cross was flicked on too Ross McCormack, who was completely unmarked and headed in at close range. It was the first time Motherwell had scored against Saints all season, and at exactly the same time Dunfermline took the lead against Caley Thistle.
A bad day was on the verge of getting even worse five minutes after the restart when Saints player/assistant manager Andy Millen deliberately handeled the ball inside the box, with McCormack slotting it away.
The penalty may have been a blessing in disguise. MacPherson was about to make one change but decided to make two - replacing Millen and the ineffectual Alex Burke with John Sutton and the much derided Mehmet. And boy, did it work.
Just two minutes later, Sutton got his head to a cross from Alan Reid. It was straight at home keeper Colin Meldrum and was incredibly tame, but inexplicably the former Kilmarnock man let it squirm through him and into the net. Shades of Alan Main exactly six years ago anyone?
The noise from the massive Saints support - far louder than the Motherwell one, even when they were winning - was incredible. Game on.
Three minutes later it was all square, Mehmet brilliantly curling a shot into the far corner and giving Meldrum no chance. The big striker gets a fair bit of stike from several folk - including me - and I'd far rather the chance had fallen to Sutton, but it was a fantastic finish and he deserves a hell of a lot of credit for it.
The momentum was clearly with Saints by this point, but Motherwell weren't giving in and McCormack twice went cross, forcing Chris Smith to tip the ball away for a corner - once from a good lob looking lob.
All ears were on Inverness, and there was at least one false roar during the course of the afternoon. However, with thirteen minutes left there was a genuine one when news came through that Caley Thistle had equalised.
Saints went close to an equaliser in a stramash that somehow squirmed away, before - with just six minutes left - Sutton cracked in a fantastic shot from Shuggy Murray territory to put Saints in front and send the Saints fans wild.
Things couldn't get any better, could they? Indeed they could - in the 89th minute there was a massive cheer, with the news that Caley had scored the winner. Saints were staying up!
Three long, agonising minutes of injury time passed before the final whistle went, the score at Inverness was confirmed and everyone could celebrate. The scenes and noise were incredible, beating anything from last season - and as we won two trophies that's some going!
At full time there was also some amusement from Motherwell fans throwing their season tickets onto the pitch. A massive gesture - except they've no more home games. Muppets.
A historic, second straight SPL season has now been secured, and if we win next week and Motherwell don't we'll finish 10th. Unbelievable.