Sterling scored his first goal for the club with the winner against Reading.
"I think he has been a great surprise to everyone; not that he is doing so well at this level but I don't think anyone expected him to break through so early," Gerrard said.
"I think we all knew he was going to be good enough to play for the first team but when they are young and small and that size sometimes you need to take a little bit extra care.
"They get used towards the end of the season to give them a taste but the manager has come in, seen what he has done in pre-season and said he is ready now.
"He hasn't let anyone down and he's been sensational so far.
"First and foremost he has the trust of the manager. He is the one who picks the team and week in, week out he is getting a start.
"That is what you need when you break through, you need the manager to believe in you because sometimes it is hard to play well every game."