Thistle were on their travels when they faced Edinburgh City in the second round of the Scottish Cup.
They started brightly and Munro should have had his side in front early on when Gough sent in an inviting ball but the striker’s effort flew over the bar.
Barnes was next to come close when he forced a good save from Lewis with a dipping effort.
On the half hour Thistle deservedly took the lead when a long ball into the box from Gorgon was met by Black in the home defence but his header back to his ‘keeper was woefully short with Munro reading the situation well to latch onto the loose ball and fire past Lewis with a composed finish.
Despite being in front Thistle were playing well within themselves and failing to turn their superiority into goals.
Just after the hour mark Thistle doubled their advantage when Barnes picked out Petrie whose shot was parried by Lewis but Jukes was alert to nip ahead of Reid to the loose ball and fire home.
Five minutes later Jukes turned provider as he picked out Shepherd with a pinpoint pass, but the midfielder opted to shoot from the angle rather than cutting back to the unmarked Petrie and although he beat the keeper his shot cannoned back of the upright.
Just two minutes from time Thistle conceded a penalty when Walker sent Lamb tumbling to the ground.
Lamb dusted himself down to take the spot kick but Henderson produced a good save before Carson cleared the danger.
Alba Mortgage Solutions Man of the Match – Liam Carson
Team – Henderson, Ireland (McShane 58), Gorgon, Carson, Gough, Shepherd (Cameron 77), McArthur (Capt.), Foulkes (Moir 58), Jukes (Walker 82), Barnes, Munro (Petrie 50)
Tomorrow (Saturday) Thistle travel to face Rosebank.