Kelleher kept a clean sheet in the Europa League win against LASK and will play against Fulham on Sunday.
“Yeah [I can step up] it's just what I've always trained for really," Kelleher said. "I know it's obviously been a long time [since I've been in the team], but I'm always training for that, to try and be ready and if something does happen to Ali – unfortunately something has – then I'm ready to go in and try to help the team get some more wins.
“It was a good performance tonight and that gives me confidence to build on and hopefully I can back that up with another good performance on Sunday.
"In this league every game has become important and we can't slip up. It's going to be a tough test with Fulham coming here looking to cause an upset. We need to be ready for that.
“We're trying to create that fortress again (at Anfield) and trying to win every game here. It is a really difficult place for teams to come and we are trying to use the crowd. We are just trying to create that fortress here and get more wins."