The 25-year-old is expected to line up for Celtic when they play Barcelona at the Nou Camp on Tuesday night and the Wales international believes that it will be his biggest ever game.
Ledley said: "Without a shadow of a doubt, it will be the biggest game that I will ever play in.
"I will be playing against the best players in the world, against the best team in the world.
"I will look forward to it. It will be a great challenge for me and the players and we just need to go out there and give 100%."
Ledley has scored 16 goals in 96 appearances since he joined the SPL club from Cardiff City in 2010.