Momo Sylla capatalised on a mistake by Rangers' goalkeeper Christiansen to put Celtic in front after only three minutes, and it looked as though the youngsters could repeat the success of the first team on Saturday.
Rangers, however, equalised early into the second half, Namouchi was the goalscorer.
It was a dissapointing result for Willie McStay's side, but Celtic still remain at the top of the Under 21 table.