The Bhoys still finished as group leaders and progressed to the knockout rounds. Cluj also secured their spot in the Europa League last-32 with this win.
Goals from Andrei Burca and Damjan Djokovic sealed the victory for the home side. As a result, Lazio were eliminated despite their victory over Rennes.
Neil Lennon made several changes to the side that won against Rangers in the Betfred Cup final. The Celtic boss handed a debut to teenage midfielder Scott Robertson.
The 18-year-old looked calm, composed, and produced a tidy performance. Former Celtic striker turned popular football pundit Chris Sutton took to social networking site Twitter to express his reaction.