The Possil outfit had blasted out of the traps with striker Paul Maxwell's aerial ability posing countless problems for a visiting Ayrshire backline shorn of commanding stopper Creag Little's height through his holiday commitments.
Maxi had come close to opening the scoring on a couple of occasions and big centre-back Jim Smith had sent a header inches over the crossbar prior to Stevie Rankin's side finally getting their noses in front in 18 minutes as a route-one ball from just outside their own penalty box saw Maxi rise highest to direct a header inside the far post, though Largs keeper Stevie Connick will probably feel he should have done better with the striker's effort.
Thistle continued to struggle with Ashfield's physical threat at set-pieces. However, they began to assert themselves in the forward areas with bustling frontman Andy Monaghan particularly prominent and he appropriately figured in their 33rd-minute equalising strike when his header across goal was diverted into his own net by Ashfield midfielder Lee McShane.
Controversy erupted just minutes into the second period when Ashfield netted what looked a legitimate score only for whistler Steven Reid to rule Shaun Fraser's goal as offside, and salt was rubbed into the wounds as Largs took the lead thanks to Willie McClure prodding the ball home in a melee following a free-kick.
Within minutes, Ashfield were back on level terms as substitute Ally Martin's shot found the net and the home side's comeback looked complete when Mark Thomson netted from a penalty kick awarded when Chrissy Hall was sent clean through on goal only to be downed in the penalty area by a despairing Eddie Walton tackle.
The referee's decision that the challenge did not deny an obvious goalscoring opportunity proved crucial with just three minutes remaining when the Largs centre-back made the scoreline read 3-3 from a Gus Galt free-kick much to the ire of Ashfield gaffer Stevie Rankin.
He said: "It was a straight red card without any question and I'm disappointed in Steven, who is undoubtedly one of the better officials doing the rounds.
"Apparently, he didn't take action because he wasn't sure who made the challenge, but surely that's where his assistants can play a part.
"They certainly had their say in denying Shaun's goal, which was as clear a goal as you ever will see, and it is just nonsensical that it was ruled out.
"I'm disappointed with a draw, but it's only half time and we can play a lot better down at Largs."
Upbeat Thistle boss Sandy McLean said: "We went there last night with the aim of keeping the play-off alive going into tomorrow's game at our place and the guys have certainly made sure of that."