"With Aaron Mooy leaving there is a bit of a replacement phase to happen and the quality of the players that we have coming through is really exciting," O'Neill told reporters on Tuesday.
"We're all looking at that spot and there's quite a few of us.
"What is important as well is that we're playing for our club, playing consistent football and in good form as well.
"It's such a good group to be involved with, we come here and we just enjoy ourselves so much and really push each other."
Former Melbourne City midfielder O'Neill, 25, has started all six games so far in his first season with Standard de Liege but has yet to win any.
"It's all part of football. You're not always going to be in a dominant team - some players might be," he said.
"But it's a challenge that I wanted as a person and as a footballer as well, to grow and improve as a player.
"Making the step back over to Europe and a really good league in Belgium is something that I'm really enjoying and just kind of taking in my stride."
O'Neill has adapted to a quicker speed and less time on the ball in Belgium, which he believes will help him at international level.
"You definitely don't get that time and you've got to make sure that you're on it, because they've got some very good players in the league there," he said.
"You've got to improve as a player, that's for sure."
Next up: world No.12 Mexico at a packed AT&T Stadium in Dallas.
"Playing these calibre teams is perfect for the experience, you learn so much," O'Neill said.
"With the group (of players) we have, and how well they did at the World Cup, it's warranted these big games that we're playing (against) top opposition on the international stage.
"Everyone wants to play against the big nations. It's what we want and where we want to be and what we strive to be."