John Sutton and Stephen McManus were the home side’s heroes, each scoring late headed goals to allow Motherwell keep the pressure on second-placed Aberdeen who had won their match at lunchtime.
In a topsy-turvy encounter, Partick came close to taking the lead when Conrad Balatoni headed narrowly wide from Kallum Higginbotham’s corner on 29.
But seven minutes later struggling Thistle did open the scoring when Higginbotham slipped the ball through to Chris Erskine who found the bottom left-hand corner of the net from 12 yards.
However, the lead lasted only five minutes with the hosts levelling matters though Keith Lasley whose shot from outside the box took a massive deflection and flew high into the net over stranded keeper Paul Gallagher.
Ian Vigurs just failed to fire Motherwell ahead shortly after the break, although the home side did not have to wait long to celebrate a second goal as Lionel Ainsworth latched on to James McFadden’s measured assist to score from inside the area.
Vigurs went close again before the final frantic 24 minutes of the match yielded four more goals.
Higginbotham made it 2-2 from the penalty spot after Ainsworth had fouled Aaron Taylor-Sinclair.
And the same player was on target again six minutes later with a low strike into the far corner from a difficult angle.
But with Motherwell seemingly slipping to a shock home defeat, Sutton and McManus turned the game on its head with goals in the final six minutes.
First, Sutton headed home from close range following Ainsworth’s floated cross, before McManus snatched the winner on 88 when he headed Steven Hammell’s whipped free-kick high into the net from seven yards.
As the visitors chased a late equalise Balatoni headed over from inside the box but Motherwell held on to boost their already strong chances of playing in Europe next season.