Neil Lennon says he needs to change the "culture" in the Celtic dressing room after detecting a lack of hunger among his squad.
The Parkhead boss was left fuming at the way his team performed in their 4-1 defeat at home to Sparta Prague.
Lennon says that there's no defending tonight's performance, and believes his players were "lackadaisical and lazy" when it mattered.
When asked how he gets his Celtic players back firing at the levels the need to be at, he told BT Sport: "I'll have to change the culture. I'll have to have a sea change over the next couple of days and get back on point.
"We go from playing really well in the semi-final to an insipid performance tonight. I defend the players to the hilt, but I can't defend that tonight."
Lennon added: "From where we were this time last season. I don't know if it's complacency, but there's a definite lack of hunger there tonight and that's really disappointing because these players have gone to the well many, many times.
"But that's not acceptable. It's not good enough. Fingers will point at the manager which is fine, but we sent a strong team out tonight but they were lackadaisical, lazy at really important points of the game and Sparta really deserved their win which is tough to say."
