Thistle proved to be a prickle for their Wigtownshire visitors, with goals at the end of either half leading to Stranraer’s Firhill downfall.
Lee Ashcroft opened the scoring right before the break, before Tony Watt made the most of some tired legs to secure the win.
Mark Wilson’s team opened the competition last Friday with a decisive demolition of Edinburgh City at Meadowbank.
Stranraer arrived at the Wyre Stadium following a dramatic upset victory on penalties over Ross County.
With Manager Chris Aitken still unavailable due to family commitments, Assistant Manager Stephen Aitken assumed the responsibility of leading the team from the dugout.
Only one change from the sensational scything of the Staggies, with James Dolan making his first start since returning from Spain, replacing Daniel McManus who dropped to the bench.
The Blues recognised that securing another unexpected victory over a full-time Championship opponent could potentially position them at the top of the group following the first two matches.
Thistle dominated the opening fifteen minutes; the visitors making two strong defensive blocks and relying on the far post to keep the game scoreless.
The Jags maintained their pressure, but a resolute Stranraer limited their chances with an excellent defensive shape, and a desire to prevent any danger.
Sallu Turay provided occasional attacking opportunities for the Blues, twice finding space to attempt shots on goal.
Both efforts were ultimately off target, failing to test former Stranraer goalkeeper Lewis Budinauckas.
Turay played a key role in orchestrating the visitors’ most promising opportunity, linking up well with James Dolan, who found Sean Docherty inside the penalty area.
Docherty came close to bundling the ball home for the Blues, but a combination of a Thistle defender, the post and Budinauckas prevented Stranraer taking the lead.
Thistle promptly capitalised on the counterattack, securing the opening goal just before half-time.
A foul committed by Beejay Coll resulted in Thistle being awarded a free kick directly in front of the away supporters.
Logan Chalmers delivered to the back post, where Partick captain Lee Ashcroft headed the ball into the net from close range.
This would be the last action of the first half, with the visitors only a few seconds from going in level before Ashcroft’s opener.
Looking for an attacking spark to spring Stranraer into life, Daniel McManus replaced Sean Docherty at the break.
The Championship side would have the first major opportunity of the second half, thanks to an error by the visitors.
A weak back pass failed to reach goalkeeper Josh Lane, allowing Logan Chalmers to chip the ball over Lane, but it would hit the crossbar and bounce to safety.
Tommy Sharp replaced James Dolan in the fifty first minute, aiming to repeat his goal-scoring exploits from Saturday.
It was proving to be another solid defensive workout for Stranraer, needing to bide their time and throw their bodies at the ball, with Thistle dominating possession in search for a second.
Evan Dunne cleared off the line and Josh Lane made several big saves to keep the Blues in the game.
Aitken brought on fresh legs in Ryan Edgar, Aaron Quigg, and Kirk McKnight to spark a comeback, but it was a substitute from the hosts who ultimately decided the outcome.
Paddy Reading’s long-range, deflected effort required Lane to make a crucial save, tipping the ball over the crossbar.
Soon after coming on, debutant Tony Watt smashed home a shot from the resulting corner to all but seal the game in the final minutes.
The Blues put up a strong fight, taking a top Championship team to the wire for the second time in three days.
Partick Thistle are currently at the top of Group B with six points, while Stranraer are in third place with two points, just behind local rivals, Queen of the South.
The Blues will now travel to the capital on Saturday for the third match of the Premier Sports Cup group stage, where they will face fellow League Two side, Edinburgh City.
Partick Thistle: Lewis Budinauckas; Cammy Logan, Lee Ashcroft, Dan O’Reilly, Paddy Reading; Luke McBeth (Zander MacKenzie 60), Robbie Crawford (Matthew Falconer 90), Ben Stanway (Thomas Horn 68); Steven Lawless (Che Campbell 90), Logan Chalmers, Aidan Fitzpatrick (Tony Watt 60).
Not used: Trialist, Nick Lockhart, Liam Dolan, Jamie Low.
Stranraer: Josh Lane; Evan Dunne, Scot Rough, Lewis Reid, Beejay Coll; Lewis Hunter (Aaron Quigg 63), Jordan Stuart (Kirk McKnight 74); Sean Docherty (Daniel McManus 45), Mark Russell, James Dolan (Tommy Sharp 51); Sallu Turay (Ryan Edgar 63).
Not used: Ewan Henderson, Finn Ecrepont.
Referee: Duncan Nicolson
Attendance: 1952
HT 1-0
