St Mirren dominated the opening 20 minutes of the game, forcing Motherwell keeper Dan Twardzik to make early saves from Callum Ball, John McGinn and Gregg Wylde.
An overzealous challenge on Lee Erwin then saw St Mirren’s Jim Goodwin earn a caution from referee Calum Murray.
Motherwell edged their way back into the game and Stephen McManus almost put them in front midway through the first half when he almost got on the end of a corner for the home side.
Moments later former Rangers man Nicky Law fired a shot straight at St Mirren’s Slovakian goalkeeper Marian Kello.
Wylde almost put the away side in front on the stroke of half-time after getting in behind the Motherwell defence but his shot failed to trouble Twardzik.
The away side began the second half as they ended the first with Wylde, Ball and James Marwood all testing Czech-born keeper Twardzik.
And St Mirren were made to pay for some wayward finishing on 63 minutes. Will Ainsworth’s shot was parried by Kello and Erwin was on hand to slide the ball home for his first Motherwell goal.
Ball should have got the away side level shortly after but somehow managed to fire the ball over the crossbar from close range.
St Mirren’s hopes of getting back into the contest looked to have disappeared with just over a quarter of an hour left when Goodwin picked up his second caution of the game for what looked like dissent.
But they had a late penalty shout when the ball appeared to strike the hand of a Motherwell player in the area but referee Murray was unmoved.
Jason Naismith and Ross Caldwell also managed late efforts but were unable to find the back of the net as St Mirren slipped to defeat in a match they will feel they deserved something from.