The Parkhead club beat Forfar Farmington 5-2 at Station Park in the second round on 23 June. But they listed 19-year-old Scotland midfielder Emily Thomson as a substitute despite the fact she no longer played for them.
Thomson told Celtic in late May that she intended to move to champions Glasgow City. Rather than release her immediately, Celtic invoked a clause which entitled them to hold on to her registration for 28 days.
Although this prevented her signing for City until 24 June, Thomson left Celtic and started training with her new club.
Forfar officials were therefore surprised to see her name on the Celtic team sheet before kick-off. Coach Mark Nisbet said: “We assumed Emily was still registered with Celtic, and that they were trying to cup-tie her so she couldn’t play for Glasgow City in the competition. When we later checked the registration with SWF (Scottish Women’s Football) it had seemingly run out the day before.”
Forfar duly filed a complaint with SWF, whose disciplinary committee is due to hear the case today.