Steven Anderson's second goal in two games since joining Partick Thistle on loan guided the Jags to a 1-0 William Hill Scottish Cup fifth-round win at East Fife.
The St Johnstone defender got on the end of a Craig Slater corner to settle this clash after also finding the target in the 2-1 win at Inverness last weekend.
Aidan Fitzpatrick dragged an early shot wide before Christie Elliott headed a Slater free-kick narrowly over as Thistle made a bright start.
Fitzpatrick was proving to be a thorn in the side of East Fife and he headed another chance wide from Miles Storey's cross midway through the first half.
The 17-year-old then turned his man well in the box but could only shoot tamely at Brett Long.
East Fife were awarded an indirect free-kick five yards out five minutes before the break when Conor Hazard caught his clearance after it was blown back by the wind but the free-kick from Scott Linton was deflected behind for a corner.
And the goal that the Jags had been threatening came after 60 minutes when Anderson headed home Slater's corner at the back post.
Ross Davidson then forced a save from Hazard when Linton's long throw found its way to him but the visitors held out for victory.