Simeon Jackson's earned St Mirren their first away win of the season and dragged Motherwell closer to the Ladbrokes Premiership relegation battle.
Saints manager Oran Kearney had urged his team to pull Motherwell back down towards them and they responded with a 1-0 win at Fir Park thanks to Jackson's close-range effort on the rebound.
Motherwell had the chance to move 12 points clear of danger but they struggled for creativity and St Mirren made a rare chance count midway through the second half to cut the gap to six and jump three points above bottom side Dundee.
Motherwell manager Stephen Robinson – who began a three-match touchline ban – brought back the five players he rested during Wednesday's defeat by Celtic but there was little sign of any spark in a forgettable first half.
Curtis Main had by far the best chance when Richard Tait's cross offered him a free header six yards out but the Motherwell striker didn't make the right contact and Dean Lyness comfortably held.
A couple of David Turnbull crosses deserved better response from his Motherwell team-mates but there were precious few other moments of skill or composure on the ball.
St Mirren did not look like threatening from open play and most set-piece deliveries were lapped up by home goalkeeper Mark Gillespie.
The visitors' first real chance came after a poor attempted clearance from Christian Mbulu five minutes into the second half but Jackson was equally unconvincing with his shot and it trundled into Gillespie's hands.
Tait enlivened proceedings with a stepover to jink past Paul McGinn before fizzing in a square ball which Danny Johnson flashed just over first time.
But it took an intervention from the sidelines to open the game up as St Mirren brought on Cammy Smith and Adam Hamill to play either side of Jackson. Robinson responded by bringing on midfielder Gael Bigirimana for defender Mbulu and moving to a 4-4-2.
The visitors began getting more bodies forward and they got in behind for the first time in the 68th minute. Smith's shot from the inside-left position was stopped by Gillespie but Jackson forced the ball home from close range.
Motherwell almost levelled six minutes later but Lyness stopped Main's header on the line, and the goalkeeper again saved a Main header after punching Turnbull's 35-yard strike towards the penalty spot.
Robinson brought on strikers Ryan Bowman and Conor Sammon and moved to four up front in the 81st minute but Hammill forced a good stop at the other end after a slick one-two.
Motherwell had one last chance but deep into stoppage-time but Lyness saved Turnbull's close-range header at his near post.