Thistle travelled to Kinghorn for a match that would see the winners move into top position in the league.
United took the lead with just over a minute on the clock when James slammed the ball home.
Worse was to follow when McPhail fired home.
Thistle pulled a goal back when McArthur stole possession and spotting the keeper well out of his box he despatched a perfectly weighted chipped shot from all of 40 yards.
McPhail and Sartarello combined to open up the Thistle defence again after 26 minutes when the latter cut the ball across the face of goal to the unmarked McPhail who slotted home
Just two minutes later it was 3-2 as Thistle pulled a goal back when Petrie slammed the ball past Downie.
On the brink of halftime United restored their two goal advantage when Sartarello beat Wishart.
Thistle halved the deficit when Barnes showed excellent awareness to pounce on a short pass back and beat stranded keeper.
After 56 minutes Thistle were back on level terms when Petrie showed great composure to ram the ball low into the net.
It was to take only three minutes for United to get back in front completely against the run of play when Gorgon was harshly adjudged to have fouled Sartarello in the box resulting in a spot kick which Summat placed past Wishart.
The visitors again got back on level terms when Palacios and McArthur combined to great effect with the latter sending a perfectly weighted pass through to Barnes who gave Downie no chance with his pinpoint finish.
United grabbed a controversial winner after Duffy collected a long clearance from a clearly offside position but he powered in on goal undeterred as Thistle protested and calmly slotted past the advancing Wishart.
This weekend Thistle host to Stenhousemuir in the Scottish Cup at St Andrews Uni.