Forrest was causing the Rangers defence some problems with his close control which brought in some hefty challenges although Rangers keeper Adams was rarely tested with the visitors defence holding firm.
Three minutes into the second half Forrest was booked for complaining to referee Dallas after taking another kick on the ankles.
Rangers took the lead in the 51st minute when Campbell raced onto a through ball before shooting low and across Daniel Giordano into the far corner of the net.
Sean Fitzharris and James Keatings were having some success down the flanks but there was a lack of punch to the Celtic attack.
In the 75th minute Rangers doubled their lead when Hemmings wrestled away from Matt Hughes before slotting his shot beyond Giordano.
Greig Spence and Atajic were thrown on in place of the Twardzik twins as Frail attempted to vary things up front and with three minutes left Atajic bravely dived in front of Adams to head a cross from Declan Gallagher into the net.
Atajic’s involvement in the game ended at that stage, play was held up as he received treatment with the former Malmo striker having his left leg immobilised before making his way to the dressing rooms on crutches.
Play was held up for a few minutes as Atajic received treatment with Marsden sent on in search of an equaliser.
Spence could have salvaged a point for Celtic in injury time when Declan Gallagher’s header fell his way in the penalty box but as he lifted his shot over Adams the ball fell inches over the crossbar.
STARTING TEAM: Guardino; Towell, Hughes, D Gallagher, Lowden; Fitzharris, G Gallagher, F Twardzik (Atajic 83, Marsden 88), Keatings, Forrest, P Twardzik ( Spence 76)
FINISHING TEAM: Guardino; Towell, Hughes, D Gallagher, Lowden; Fitzharris, G Gallagher, Keatings; Forrest, Marsden, Spence