Our American star knows the double SPL winner better than most having spent three successful seasons with him at Leicester City between 1996-99.
O'Neill led the Foxes to promotion, four top 10 Premiership finishes and three League Cup Finals, winning in 1997 and 2000 (losing to us in 1999) and onto Europe twice before departing for Glasgow where he took the title back off Old Firm rivals Rangers in his first season and held onto it last term.
Keeper Kasey will now meet up with his former boss in our friendly clash at the Lane tonight (8pm).
"Players don't want to disappoint him and that's a big strength," explained Kasey. "He goes into every game with everyone 100 per cent ready to do well for him.
"There were times when I didn't know what it was about him and I was playing for him. The team is ready to play every game and he's proved that again at Celtic.
"There is something there and he definitely gets the most out of everyone who is playing for him. He wants to win and there is an attitude of winning and you can't beat that.
"As a manager he has a bit of everything. At times he's a talker, at times he's a shouter, at times you don't want to be on the other side of the conversation and at times you want to be there.
"He's 100 per cent honest, you know where you stand and you know what you want to do for him.
"We had some very good years at Leicester and things have continued to go great for Martin.
"He has done tremendously well at Celtic, two titles and they will look for European success as well. You can't say more about what he's achieved."
Kasey Keller admits even he can't quite put his finger on that certain magic about Celtic boss Martin O'Neill.