Motherwell started life under Graham Alexander with a point away to St Mirren.
Devante Cole’s first-half goal was cancelled out by Jamie McGrath’s penalty in the second to ensure a 1-1 draw.
Motherwell started lively in attack, with players being positive with the ball at feet and running at the home defence.
Jamie McGrath and Marcus Fraser fired wide in forays forward for the hosts but it would be the visitors who would have the best of the early chances.
Watt should have had Motherwell ahead on 22 minutes. A perfectly floated ball from deep by Polworth was into the path of the onrushing forward. From 10 yards, he had time to adjust for the header but failed to generate enough power to steer it past Alnwick.
Watt then turned creator soon after. A clipped ball in-field from the right was picked up by Cole 25 yards out. He drove into the space, before dragging his shot from the edge of the box just past the left-hand post.
The breakthrough would eventually come in the 27th minute.
The impressive Polworth sent in a corner from the left which was half-cleared into the Paisley sky.
As the ball came out of orbit, Watt positioned himself to head back across goal and Cole was on the spot to sweep through the crowd of bodies and into the net.
Motherwell continued positively, with the Saints restricted to long balls in behind and set plays which were causing trouble, but got the Steelmen in ahead at the interval.
A balanced start to the second half saw Saints have half chances, with Ethan Erhahon going closest before the hour mark with a shot dragged wide of the left post.
Motherwell were being pinned deeper and were made to suffer when St Mirren got a penalty, with Erwin going down in the box.
McGrath rolled the ball into the bottom left corner to equalise, sending Kelly the wrong way.
But the Steelmen could have stole it at the death. Mark O’Hara’s free-kick from 30 yards was bound for the top left corner, only for ‘keeper Alnwick to get across brilliantly and steer it wide.
Motherwell: Kelly, O’Donnell, Mugabi, Gallagher, Carroll, O’Hara, Campbell, Polworth, Hastie (White), Cole (Maguire), Watt.
Subs not used: Morrison, Devine, Cornelius, Crawford, Seedorf, Grimshaw, McGinley.