Pedro Porro canceled out Hugo Ekitike's opener for Eintracht Frankfurt in the first-leg of their Europa League quarterfinal.
Afterwards, Postecoglou said: "A little bit frustrated by the result obviously but I thought the performance in general was really good from the boys. We conceded early which was not ideal and it was a fair strike by the lad but I thought our response to that was really good. We stayed in control. We scored a good equaliser.
"We made them work hard in the first half so we knew in the second half, with our ability to break teams open, we would put them under pressure. It is exactly what happened and the boys did everything right.
"I couldn't ask for anything more from them. We hit the crossbar three times, their keeper has made some amazing saves. We had a couple of other good opportunities as well. On any other night we would have a comfortable victory. If we can perform like that over there, and there is no reason why we can't, then we still give ourselves a good chance."
He added, "I think the guys coming on today made a difference and injected some energy. It could be tight next week, it could go into extra time and we are going to need everyone ready to go and the beauty of things at the moment is we have a squad ready to go and that will be important next week."
On winning in Germany for the second-leg, Postecoglou insisted: "If we can repeat that next week, and there's no reason we can't, we'll give ourselves a good chance. I really felt like we overwhelmed them with our football, with our running and with our press. It wasn't just the chances we created but the chances we almost created.
"It's going to be that sort of season. Nothing is going to come to us easy. We're going to have to go there and fight now to get what I thought we deserved tonight and that's what we'll try to do."