Killian Phillips opened the scoring for Saints in the 39th minute of a frenetic and open match which barely took time to draw breath.

Mark Wilson’s men stepped up after the break and levelled in the 62nd minute through an Aidan Fitzpatrick strike with the Buddies defence in tatters.

Both sides gave their all in search of the winner but the match ended all square and the tie will be decided in Paisley on Monday night.

St Mirren, who won the Premier Sports Cup final in December before finishing second-bottom of the top flight, may believe home advantage will see them through but the Maryhill men, who have lost out in the play-offs in the last four years, will have plenty to say about that after giving as good as they got against the visitors.

Phillips, deployed by interim boss Craig McLeish almost as a striker alongside the powerful Mikael Mandron, had a couple of early efforts blocked inside the Jags penalty area which signified his intent.

In the eighth minute, Fitzpatrick cut in from the left and curled a shot from the edge of the box just past the far post.

Phillips had another shot deflected wide for a corner from 16 yards after a terrific move down the right involving Mandron and Richard King.

At the other end, good goalkeeping from St Mirren’s Ross Sinclair thwarted Alex Samuel after the Jags striker had bustled past Alex Gogic to latch on to a sloppy header from King.

Thistle keeper Josh Clarke saved a low drive from Phillips, who was sent through by Mandron, then more lax play from St Mirren midfielder Jacob Devaney allowed Tony Watt get clear and fire in a shot which Sinclair parried.

Phillips got the goal he clearly coveted when he took a pass from the excellent Mandron inside the Jags box and stabbed the ball past Clarke.

However, just before the break, Jags captain Lee Ashcroft passed up a great chance to level when he headed a Fitzpatrick corner past the post from six yards.

Ts’oanelo Lets’osa replaced Logan Chalmers for the start of the second half as Wilson tweaked his side and battle recommenced.

There was a scare for the home side when Mandron dispossessed the ponderous Clarke inside the box as he dallied in possession but when the ball fell to midfielder Allan Campbell, his lob was yards wide of the target.

On the hour mark, Fitzpatrick’s attempted pass back from distance was intercepted by Mandron but his shot was straight at Clarke.

However, the Thistle wide man made up for that misjudgement when he calmly converted Watt’s cross from the right, which found him unmarked 14 yards from goal.

The Jags were on top but could not find another breakthrough.

Substitute Gary Mackay-Steven struck the inside of the far post in added time but the offside flag went up.