The first half was a tight affair with Leicester striker Paul Dickov forcing a save out of David Lucas early on and Fuller having two shots.
Eddie Lewis, the USA international, had a shot and Fuller had a 20-yard strike which hit the roof of the net.
Erik Skora forced a save out of Ian Walker and with ten minutes to the break an eight-yard shot by Fuller was deflected by Walker on to the left-hand post from a Skora pass.
The fourth official indicated two minutes extra time and Muzzy Izzet was booked for a foul on Skora.
In the 48th minute Fuller made it 1-0 with a six-yard right-foot shot into the bottom left from a long free-kick by Lucas.
Gerry Taggart was booked for a foul on Richard Cresswell and the injured Jordan Stewart was replaced by Trevor Benjamin.
Preston old boy Billy McKinlay came on for the injured Alan Rogers.
Taggart hit the bar with a header with six minutes to go from Izzet's corner.
Brian Deane was replaced by Jon Stevenson with five minutes to go and two minutes later Craig Brown brought on Marlon Broomes for Lewis.
Fuller scored his 11th of the season with a great individual run down the left before firing into the bottom corner of the net to cap a superb performance.