Match ends, Partick Thistle 1, St. Mirren 0.
Partick Thistle progressed to the quarter-finals of the Scottish League Cup after triumphing over St Mirren in extra-time.
Following a tightly contested 90 minutes, a Nathan Eccleston strike was enough to send the hosts through.
The forward took advantage of weak Buddies defending to tap in a rebound after stopper Marian Kello's save from Christie Elliott.
Kello had earlier saved a header from Conrad Balatoni.
And the Jags, who lost to St Mirren on league business four days previously, merited their place in the last eight having created the better chances.
However, neither side were particularly enterprising in the first half.
Kris Doolan was handed the first opportunity following good touches from Lawless and James Craigen, but he curled wide from 16 yards.
St Mirren, who were missing Ellis Plummer to injury, also lost Gary Teale after he came off worse in a shoulder charge with Jake Carroll.
The visitors were looking sharper in possession but any promising move broke down outside the penalty box, as St Mirren had a half chance to snatch an interval lead.
Gregg Wylde's cross found Kenny McLean's untracked run with home goalkeeper Scott Fox off his line, but the midfielder glanced his header wide.
The game immediately opened up after the restart and Kello palmed away a headed attempt from Balatoni.
Alan Archibald's charges were moving the ball much quicker and they kept the pressure on with Carroll fizzing a shot wide.
McLean headed wide again, this time following a deep corner, but Saints found themselves in trouble after another corner was cleared.
Lawless set substitute Ryan Stevenson away with an excellent first-time pass but he shot straight at Kello from 25 yards when he had support arriving to his left.
In the closing stages of the 90, Thistle put themselves under pressure with some sloppy defending and visiting right-back Adam Drury burst forward found Reilly in space, but the striker's shot was palmed out by the impressive Fox.
Reilly took the resulting corner and presented McLean with a free header but he again headed just wide with his best chance so far.
In extra-time, substitute James Marwood was almost the hero for St Mirren when he found space for a shot, only to see it comfortably collected by Fox.
And the winner arrived at the other end. Former Liverpool and Blackpool striker Eccleston had all the time and space he needed to slot home after Kello had stopped substitute Elliott's shot.
Chances were few and far between throughout the rest of extra-time and the home fans were soon celebrating their place in the next round.
Partick Thistle manager Alan Archibald: "We got the win in the end. I thought we deserved it; we had enough opportunities to win the game in normal time but we just picked the wrong option in the final third.
"When we played short, sharp and crisp it was good, and I thought in the second half we created more chances, but we have to be more clinical.
"We didn't have to say much to get the players motivated, after Friday's defeat, and I thought we got the reaction.
"I was delighted with the players who came in tonight - they made a real difference; Christie Elliot setting up the goal and Nathan Eccleston scoring.
"The boys will take a lift from this result, and getting a clean sheet into the bargain, so it can only help our league form."
St Mirren boss Tommy Craig: "It was an awful game; no flow to it and no class and, quite frankly, I don't think either team deserved it.
"Our lack of fluency showed and we didn't dominate like I would've liked us to - my overriding feeling is disappointment.
"We were always looking to build on last Friday but we didn't show anywhere near how good we can be.
"We need to make sure we do ourselves justice in the next games; firstly against the champions and Aberdeen, and we need to give our fans something to hold on to."
- 17CarrollBooked at 105mins
- 7CraigenSubstituted forStevensonat 63'minutes
- 15HigginbothamSubstituted forElliottat 98'minutes
- 9DoolanSubstituted forEcclestonat 63'minutesBooked at 118mins
- 17DrurySubstituted forKellyat 90'minutes
- 4McAuslandBooked at 110mins
- 22TesselaarBooked at 66mins
- 21TealeSubstituted forReillyat 26'minutes
- 11WyldeSubstituted forCaldwellat 62'minutes
- Calum Murray
- Shots on Target
Second Half Extra Time ends, Partick Thistle 1, St. Mirren 0.
Attempt missed. Kenny McLean (St. Mirren) right footed shot from outside the box is too high.
Foul by Christie Elliott (Partick Thistle).
Isaac Osbourne (St. Mirren) wins a free kick on the left wing.
Corner, Partick Thistle. Conceded by Isaac Osbourne.
Corner, Partick Thistle. Conceded by Jeroen Tesselaar.
Corner, St. Mirren. Conceded by Steven Lawless.
Nathan Eccleston (Partick Thistle) is shown the yellow card.
Hand ball by Stuart Bannigan (Partick Thistle).
Attempt saved. Kenny McLean (St. Mirren) left footed shot from more than 35 yards is saved in the top centre of the goal.
Foul by Ryan Stevenson (Partick Thistle).
Isaac Osbourne (St. Mirren) wins a free kick in the attacking half.
Stuart Bannigan (Partick Thistle) wins a free kick in the attacking half.
Foul by Ross Caldwell (St. Mirren).
Corner, Partick Thistle. Conceded by Jim Goodwin.
Attempt blocked. Ryan Stevenson (Partick Thistle) right footed shot from the left side of the box is blocked.
Marc McAusland (St. Mirren) is shown the yellow card.
Nathan Eccleston (Partick Thistle) wins a free kick on the left wing.
Foul by Marc McAusland (St. Mirren).