Oldland played up the slope in the first half and the young side defended resolutely against their hosts.
In the second half, Ollie Nott grabbed the winner for Wellington with a shot that hit the post and went in off keeper Jamie Powell. Wellington held on to set up a quarter final tie at Barnstaple in March with the Devon side beating Cribbs 2-1 after extra time.
Cribbs move on and entertain Oldland next Saturday at the Lawns, kick off 3.00pm.
Oldland's belief in the youth of the club was confirmed even more with the selection of six teenagers in the squad and ten players aged 22 and under in the fifteen man group. The strike force of Lewis Powell (16) and Asher Budd (17) must be one of the youngest forward pairings seen at this level, this weekend.