McAteer is backing Brewster to make his mark this season.
Speaking to Off The Ball, he explained: "What we've seen over the last 12 months is Jurgen has found his ideal starting eleven.
"Apart from maybe one or two in that midfield - you can probably pick the rest, week in, week out.
"But there are a lot of games to be played this season in a very short space of time, plus Liverpool will want to go again in the Champions League.
"Liverpool have got some great youngsters who Jurgen has bedded in really, really well.
"He has picked his games to play them. Neco Williams has come in - he's not going to displace Trent [Alexander-Arnold], but he's certainly a good backup for him. Quite versatile as well.
"Curtis Jones you could slot in there for 20/25 minutes if needs be.
"But the big one for me is Rhian Brewster. At the beginning of last season I went away on tour with the lads in America, Rhian started pre-season really well and got the opportunity.
"It was big expectations coming back from a big injury. Jurgen let him go out to Swansea. He scored 11 in 22 and has come back with a bit of a swagger.
"I believe he is training really, really well. I think he has now stepped a little bit ahead of Divock Origi, which might raise some eyebrows.
"But I think he is ready to slot in to give a bit of rest to the front three that usually pick themselves. You can rely on him for 20 to 25 minutes."