Meetings between St Johnstone and Dundee United last season were close-run affairs.
Two goals in three games was evidence of that, with Ali Crawford's strike the difference maker at Tannadice Park last time out.
And another close contest went the way of Saints once more thanks to Perth legend Stevie May.
Both teams set up in similar 5-3-2 formations with early pressure from the home side before former Tangerine Nicky Clark saw his shot blocked after 10 minutes.
Then a cushioned ball over the top by Andrew Considine caught out the entire United defence before an onside May confidently swept the ball over 'keeper Carljohan Eriksson to make it 1-0.
Clark then saw a half volley sail over the bar a few minutes later after the Arabs failed to clear their lines effectively.
United attempted to put the pressure on, continually hitting target man Steven Fletcher who was winning most of the aerial battles, but Saints were standing firm.
Fletcher saw his header from a corner cleared off the line by goalscorer May on 24 minutes in what was the home side's clearest chance of the first half.
Clark then saw his owner goalbound header blocked off the line just after the half-hour mark.
Jamie McGrath's cross met the head of the lively Sadat Happy Anaku but he could only glance it out for a goal kick.
United had most of the ball in the first 45 minutes but Saints had little to worry about with McGrath's free kick headed over by Edwards, leaving Saints stopper Remi Matthews untroubled.
May then proved to be the key man once more just before half time, latching onto a ball over the top from Ryan McGowan and laying it off to Melker Hallberg who slotted into the bottom corner.
A sweeping move involving May and Jamie Murphy was blocked before Drey Wright fired just wide as Saints went into the break with their tails up.
Hearts were in mouths for the away support at the restart after Adam Montgomery went down clutching his leg after a foul from Ian Harkes.
Montgomery then stretched his legs and charged into the box with balance and poise before his strike was blocked.
United continued to send balls into the box which were swept away by an on-song Perth backline.
May almost got his brace just before the hour mark striking the bar with an audacious curling effort which left Eriksson stranded.
Anaku managed to get in behind the Saints backline but his effort was smothered by Matthews before Ryan Edwards headed over from a United corner.
Saints countered with Drey Wright running most of the field but his ball through to May was overhit and collected by Eriksson.
United had plenty of shots in the game but never truly troubled Matthews until the final 10 minutes.
But on a day of Nicky Clark's homecoming it was former Saints striker Tony Watt who pounced to make it 2-1 and a nervy final few minutes for the blue shirts.
It didn't matter though as Callum Davidson's men saw off the late pressure to seal the derby bragging rights and all three points.
Line-ups
St Johnstone: Remi Matthews (GK), Alexander Mitchell, Liam Gordon, Andrew Considine, Adam Montgomery, Melker Hallberg, Ryan McGowan, Jamie Murphy (Connor McLennan '71), Nicky Clark (Thelonius Bair '85), Steven May (Ali Crawford '71), Drey Wright
Dundee United: Carljohan Eriksson (GK), Liam Smith, Ross Graham, Aziz Behich, Kieran Freeman (Glenn Middleton '68), Ryan Edwards, Jamie McGrath, Dylan Levitt, Ian Harkes (Archie Meekison '68), Sadat Happy Anaku (Ilmari Niskanen '75), Steven Fletcher (Tony Watt '56)
Capacity 7977
Referee David Munro
