Kallum Higginbotham, who was on loan at Motherwell last season, almost came back to haunt the home side with two second half goals to restore Thistle's lead after Chris Erskine's opener had been cancelled out by goals either side of half-time from Keith Lasley and Lionel Ainsworth.
But Well fought back and two late strikes from John Sutton and Stephen McManus earned the the points that kept the Fir Park side third in the table.
The second-half action was in complete contrast to a dismal first 30 minutes with play either bogged down in the heavy wide sections of the pitch or a cluttered midfield.
In the opening stages neither goalkeeper looked threatened and with their first attempt at goal after 28 minutes, Conrad Balatoni should have put Partick ahead but his header from Higginbotham's corner was wide of the post.
Thankfully for both sets of fans, the game burst into life after 38 minutes when Thistle opened the scoring.
Higginbotham was allowed to run at the home defence and his through-ball found Erskine who had time to turn and bury his shot in the corner of the net despite Gunnar Nielsen getting his hand to the ball.
Two minutes later the Glasgow side might have added a second when Higginbotham was again the provider but Prince Bauben's smart drive was blocked by Shaun Hutchison on the penalty spot.
Just when the visitors looked to be holding onto their lead until the interval, Well drew level with a bit of good fortune.
Lasley cut in from the corner of the box and a wicked defection from Higginbotham carried his shot high over Paul Gallagher and under the bar.
That was just the lift the home side needed and they started the second half with more purpose. Within minutes of the restart James McFadden had found Iain Vigurs at the angle of the box but he curled his shot over the bar.
After 51 minutes, though, McFadden was the architect as Well took the lead.
After taking a pass from Ainsworth, the former Scotland international rolled the ball across the box into the path of the midfeidler whose controlled shot carried he ball high past Gallagher to make it 2-1.
Thistle had an immediate chance to regain parity but Lyle Taylor's low drive from eight yards was deflected over the bar by Stevie Hammell's outstretched leg.
The Jags pressed for an equaliser and on the hour were denied a penalty when Aaron Taylor-Sinclair's shot rebounded off a defender's arm.
A minute later the visitors were denied again, this time when Nielsen got down well to smother Bauben's shot from six yards.
Thistle were finally rewarded after 65 minutes when Ainsworth's sliding tackle caught Taylor-Sinclair. This time referee Stephen Finnie had no hesitation in pointing to the penalty spot and Higginbotham was equally confident as he smashed his spot kick high into the net to level the scores.
Thistle then had the lead in the 72nd minute when Higginbotham set off on a solo run and, after hurdling over Hutchison, he kept his cool and from a tight angle drilled the ball across the keeper and into the far corner of the net.
However, the visitors were dealt a hammer blow when Well grabbed a quick double in the last six minutes.
Ainsworth floated a cross into the six-yard box where Sutton rose to nod home his 12th goal of the season.
And two minutes from time the comeback was complete as Hammell whipped a free kick to the corner of the six-yard box where McManus met the ball perfectly to powerfully head beyond Gallagher.