The Porcupine Warriors edged the league champions 2-0 to book a date with Hearts of Oak in the semi-finals of the G6 tournament.
The game was rained off, following torrential rains in Kumasi on Sunday evening, so it was postponed to Monday.
Asante Kotoko outplayed Wa All Stars in the first half, yet fluffed in front of goal.
Back from the half time break the hosts intensified their search for goal and Emmanuel Gyamfi broke the deadlock against his former side, Wa All Stars with just four minutes into the second.
And Obed Owusu registered his name on the scoresheet with a carpet free kick to double the score line for the Kumasi giants.
Asante Kotoko have finished the group stage with two wins out of two and have scored five goals in the process: They walloped Bechem United in their opening game 3-0, before beating Wa All Stars 2-0.
The Porcupine Warriors have progressed from the group with Bechem United, who piped Wa All Stars 1-0 in their clash.
The poor display of the league champions, Wa All Stars in the G6 is very worrying, especially as the they prepare for the CAF Champions League somewhere in February, 2017.
Asante Kotoko would have to overcome Hearts of Oak in the weekend if they want to reach the final and defend the G6 title they won last season.