Inverness manager Terry Butcher described the 2-0 defeat by Celtic in the Scottish Cup as their "worst performance of the season".
Goals by Georgios Samaras and a Scott Brown penalty saw the holders progress to the last eight of the competition.
"I can't describe how disappointed I am," Butcher told BBC Radio Scotland's Sportsound.
"I've had my say with the players and they know where I stand. I'm disappointed we didn't turn up today."
Inverness struggled to put Celtic keeper Fraser Forster under pressure during a lethargic display.
And Butcher said the players had a lot to prove when they face Celtic on league duty next Saturday.
"We should be giving Celtic a better game than we did today," Butcher added. "That was like a practice game for them today.
"Celtic worked harder than us and that's a bitter accusation I can level at my team.
"That's not what we do, nor what we're all about. We just didn't perform."
On facing Celtic next weekend, he added: "That's a massive opportunity for everybody to bounce back and show me that they want to play for this club."