It was a scrappy match with the visitors unable to play their usual flowing football as Dunfermline sat in without evert posing any real threat to equalising Harper’s 23rd minute goal.
Celtic’s final Reserve Cup group match will be on December 2 against Motherwell with the winner progressing to the knock out phase.
Daniel Church captained the side from central defence alongside Dave Mackay with Lee O’Connor on the right and Toby Paterson at left-back.
Barry Coffey and Scott Robertson anchored the midfield with Dembele on the right, Oko Flex to the left with Liam Burt in the ‘Christie role’ behind Harper.
Dunfermline had looked pretty useful in the opening 15 minutes but once Celtic started to exert themselves it was one-way traffic towards the pars goal with the hoops taking the lead midway through the first half.
Scott Robertson’s free kick from the left didn’t appear to carry too much threat but when the keeper weakly punched the ball out Harper didn’t hesitate to slide the ball into the net.
Celtic had a number of other first half free kicks in the final third but were unable to add to Harper’s goal before the break.
Six minutes into the second half Dembele picked up an incredible yellow card. After being stopped near the by-line he went down to the ground. After the Celtic physio was called on to give him treatment the referee followed up by booking the young winger.
Just before the hour mark Dembele almost increased Celtic’s lead but his free kick from 25 yards out cleared the ball but skimmed the crossbar on it’s way over. Burt was next to threaten the Pars goal but a retreating defender blocked his angled drive after 68 minutes.
Celtic should have added to their lead but a second goal evaded Tommy McIntyre’s side.
DUNFERMLINE: 1 Ryan Scully 2 Matthew Bowman 3 Miller Fenton 4 Danny Devine 5 Thomas Bragg 6 Stuart Morrison 7 Joe Thomson 8 Tom Beadling 9 Gabby McGill 10 Lewis Sawers 11 Josh Coley
CELTIC: Mullen; O’Connor, Church, McKay, Paterson, Coffey, Robertson (Mazi 61); Dembele ( Conor McBride 89), Burt (Savoury 81), Oko Flex; Harper
SUBS: Liam Hughes, Finn McRobb, Ben Wylie