A 2-1 defeat in the Netherlands was enough for Celtic to secure a place in the group stage and they were drawn to meet Real Betis, Bayer Leverkusen and old foes Ferencvaros.
Postecoglou was pleased with the draw, but the progress came at a cost with injuries to Greg Taylor and talisman Kyogo Furuhashi with another big game to come when he takes his side across the city to face champions Rangers.
"I guess that's reward for Thursday and two legs against a very good team in AZ, and with the calibre of team we are going to be up against, I am super excited," Postecoglou said.
"We are going to have some fantastic nights, particularly at Celtic Park, so I am looking forward to it.
"Out of [Thursday] night, obviously Greg Taylor has got his shoulder problem. It looks like it is nothing too significant so there is still a chance for Sunday,” he said
"Kyogo got his usual bruises and knocks. He is getting tested out physically every game, I think people are figuring out that he is one of the ones they need to stop and try to find, shall I say, creative ways to do that. But he usually bounces back pretty well so I am hopeful he will be fine."
James McCarthy and James Forrest are also pushing to return for the first Old Firm match of the cinch Premiership season after missing the trip to Holland.