Kelleher heaped praise on the defenders in front of him as they go to Arsenal as Premier League leaders.
He said, "It's been a great start, obviously. It's down to a number of things. Definitely, the defensive form has been key. We have kept a lot of clean sheets and conceded less goals.
"It's not easy coming away from home but we dug in against Leipzig and defended well as a whole team, we are doing that brilliantly right now. We've put in some shifts and there have been some big blocks and big tackles to get those clean sheets."
The Republic of Ireland international added: "It's early days in the title race but it's still a massive game. We did not get the best result there last season and we will be looking to do better this time. It will be really tough and we need to be prepared. I will always back the team as I know the quality we have.
"It's going to be a tough game, obviously, it's never easy at the Emirates but we will do our best to be as well prepared as we can and we will give it a good go."