Youngster Abdul-Aziz Al-Sebiani scored the winner eight minutes past the hour mark.
Ittihad finished on top of their group with 10 points to set-up a meeting with Nassr in the competition’s semi-final.
Egypt striker Meteb made the starting line-up and was substituted two minutes from time.
He made a notable impact and was unlucky not to find the net on two occasions.
Ten minutes after the interval, Meteb latched onto a deft through pass and lobbed the keeper but an Ahli defender perfectly intervened to clear the danger.
Five minutes later, his exquisite curling free-kick was brilliantly blocked by Ahli keeper.
Recent reports suggested Ittihad were considering offloading Meteb in January although he proved a revelation since joining from Egyptian champions Ahli on a season-long loan in the summer.
Ittihad were apparently looking to make room for new foreign signings but they failed in their attempts to lure Argentinean midfielder Damian Manso.
Meteb will probably now see out the remaining six months of his loan deal.