Maddison was impressive on the night.
And ahead of Sunday's trip to Crystal Palace, Postecoglou said: "He was part of a winning team over the weekend too. I thought he played well in the first half. It was a tactical change, I thought it was needed for the team to win, but I understand the players want to play all the time.
"I thought he was really good last night. I thought his leadership throughout the game was good. He was really positive on the ball and when we needed moments of creativity or discipline, he was there."
On Mikey Moore potentially starting at Palace, Postecoglou said: "I think we all understand with young players, you have to be careful, but after the game, I don't get the sense that that's going to affect Mikey at all. There's no denying he was great last night, I thought he was great the whole game, especially that period. It's exciting for us.
"He's ready to start any game. I just feel, especially with younger players, you've got to be really careful about their introduction into senior football. He's still physically growing. You have to take that into account so I think he's ready to play, to start a Premier League game, for sure. But for me it's about making sure, for us, that we develop Mikey in the right way and so far whatever we've asked from him, he's made a good impact."