Match ends, Partick Thistle 5, St. Mirren 0.
Partick Thistle claimed their first win in this season's Scottish League Cup with a dominant display against second-tier St Mirren.
Kris Doolan's strike, two from Steven Lawless and Blair Spittal's free-kick put the Premiership side in command by half-time.
Thistle had Abdul Osman sent off before Spittal netted his second.
Also in Group H, leaders Livingston beat Airdrieonians with goals by Dylan Mackin and Craig Halkett.
Livi have eight points after three games while Thistle, who lost a penalty shootout to the leaders last week, have four points.
Airdrie and St Mirren have three points each while Stranraer, who were not playing in this weekend's first-round group fixtures, have no points.
Though they would be overwhelmed by their hosts, St Mirren could have taken the lead when Jordan Kirkpatrick's powerful long-range shot required a save from Tomas Cerny.
Thistle soon moved into the ascendancy, but there was a degree of fortune about their opener.
Spittal nodded the ball through for Doolan, who looked suspiciously offside, and the striker slotted past Ross Stewart.
Lawless played a one-two with Chris Erskine before thrashing a low shot into the far corner from the left of the box and Lawless' second was a delightful sweep into the same corner from the edge of the box.
Spittal's free-kick was struck from a similar distance as Stewart was this time beaten to his right. It was the former Dundee United midfielder's first goal since moving to Firhill.
Jags captain Osman was booked twice in quick succession for fouls on St Mirren skipper Stephen McGinn but it did not interrupt the hosts' rhythm.
They got their fifth with a stunning counter attack. Doolan released Erskine on the left and he beat his man before finding Spittal with an inviting low cross that the midfielder struck crisply and confidently past Stewart.
St Mirren sought consolation but McGinn and Ian McShane were denied by Cerny.
In Livingston, Dylan Mackin opened the scoring by converting a Josh Mullin pass and Craig Halkett headed Livi's second from Raffaele de Vita's corner.
The eight group winners and four best runners-up progress to the knockout stage where they are joined by the four teams in European competition - Celtic, Aberdeen, Rangers and St Johnstone.
Post-match reaction from Firhill
Partick Thistle manager Alan Archibald: "It was a good performance - you could see the difference having Abdul and Callum Booth back in the side today. It made for a lot of good play.
"I don't know where the performance ranks in my time here but it was very similar to our Championship-winning team when we first got promoted.
"There was a lot of similar play and sometimes it just clicks. Some of the one, two touches were exquisite."
St Mirren manager Jack Ross: "Our performance was very poor, I thought Partick's was good. When you have that combination of performances from a Premiership team and a Championship team then the outcome is the one it was today.
"We didn't do the fundamentals that'll give you a chance to win a football match anywhere near well enough. First and foremost, you have to be competitive and you have to have a desire about your play and a hunger and we didn't have that. We were short in that by a long way today and that was why we lost the game so heavily."
- 6OsmanBooked at 58mins
- 8BanniganBooked at 43minsSubstituted forMcCarthyat 83'minutes
- 10ErskineSubstituted forEdwardsat 64'minutes
- 9DoolanSubstituted forNisbetat 73'minutes
- 15BairdBooked at 37mins
- 17KirkpatrickSubstituted forO'Keefeat 47'minutes
- 11SmithBooked at 46minsSubstituted forStewartat 72'minutes
- 20ReillySubstituted forSuttonat 63'minutes
- Stephen Finnie
- Shots on Target
Second Half ends, Partick Thistle 5, St. Mirren 0.
Attempt saved. Kevin Nisbet (Partick Thistle) right footed shot from the centre of the box is saved in the centre of the goal.
Attempt saved. Steven Lawless (Partick Thistle) right footed shot from outside the box is saved in the bottom right corner.
Attempt saved. Lewis Morgan (St. Mirren) right footed shot from outside the box is saved in the centre of the goal.
Attempt missed. John Sutton (St. Mirren) left footed shot from outside the box is close, but misses to the left.
Foul by Kevin Nisbet (Partick Thistle).
Gary MacKenzie (St. Mirren) wins a free kick in the attacking half.
Substitution, Partick Thistle. Andrew McCarthy replaces Stuart Bannigan.
Attempt blocked. Stephen McGinn (St. Mirren) right footed shot from outside the box is blocked.
Corner, St. Mirren. Conceded by Tomás Cerny.
Attempt saved. Ian McShane (St. Mirren) right footed shot from outside the box is saved in the top left corner.
Attempt saved. Stephen McGinn (St. Mirren) right footed shot from outside the box is saved in the centre of the goal.
Attempt missed. Ross Stewart (St. Mirren) header from the centre of the box is just a bit too high.
Conor O'Keefe (St. Mirren) wins a free kick in the defensive half.
Foul by Danny Devine (Partick Thistle).
Substitution, Partick Thistle. Kevin Nisbet replaces Kris Doolan.
Attempt missed. Blair Spittal (Partick Thistle) right footed shot from outside the box misses to the left from a direct free kick.
Substitution, St. Mirren. Ross Stewart replaces Cameron Smith.
Blair Spittal (Partick Thistle) wins a free kick in the defensive half.