Thistle travelled to Aberdour to face newly promoted Premier League side Bayside in the first round of the North Road Garage Fife Cup.
But an abject second half performance saw the Balmullo side suffer their heaviest defeat in nearly 20 years.
Bayside took the lead after only two minutes when Foulkes made a complete hash of a clearance which fell kindly to Brechin whose effort had little power behind it but somehow managed to catch Anderson unawares as the ball found the bottom corner of the net.
Brechin added a second after 19 minutes.
Despite the early setback Thistle were beginning to play some good football but were looking toothless in front of goal with Cranston and Cameron passing up excellent opportunities.
After 57 minutes Bayside all but secured their place in the next round when a floated ball into the box was not dealt with and Kennedy took full advantage.
It was to be a horrendous three minute spell for Thistle as they conceded another two goals in two minutes firstly with a low ball into the box which somehow found its way into the net and then substitute Canning was too easily dispossessed to allow Kennedy to fire past the helpless Anderson.
It was to be four goals in seven minutes as Bayside romped to a 6-0 lead in the 63rd minute as Kennedy latched onto a long ball getting in behind the Thistle defence to slot past Anderson 1 on 1.
A Hamilton brace late on sealed the rout.
Commercial Arms Man of the Match – Kevin Ross.
Thistle – Anderson, Ovenstone, Ross, Gough, C. Thaw (Canning 47), Ireland, McGlashan, Foulkes, Kirby (Henderson 79), Cameron (Palacios 61), Cranston (Gordon 61)
Tomorrow (Saturday) Thistle host to Glenrothes Strollers in the Glendale Plastics Championship at 2pm.