Kelleher feels the squad have quickly responded to manager Arne Slot's methods in preseason.
"I think the most important thing is getting minutes and coming out with no injuries, which we've done," Kelleher told Liverpoolfc.com.
"The manager has alluded to it as well that we need to get wins, so I think we've had a good run of results against good opposition. It builds momentum for us to go into the first game of the new season full of momentum and full of confidence."
On working under Slot, Kelleher added: "It's been really good. Obviously he has a really clear way of playing and his messages are really clear. He holds us to a high standard, which we need to be held to.
"There are obviously very good players here, so he pushes us to our limits and wants us to do well. It's been really positive. It's been a lot of information to take onboard and we're just trying to work on it each game. I think it's getting better and better."
On going to Ipswich on Saturday, Kelleher said: "I think it's come around quickly as it always does.
"We've had a good pre-season. We were full of confidence coming back from the US with the results there and then seeing the other players return who went a long way in their international tournaments, having them back has been a confidence boost as well.
"So, kind of having the whole squad back this last week, we've worked hard on stuff and we're full of confidence and ready to go."