Ange Postecoglou says Celtic have earned the right to play in the Champions League and proved they belong at that level.
After another chastening week of three defeats in Europe for Scottish teams, the Celtic manager has defended his side, who have one point from four games in Group F.
"If anyone can tell me in the four games we've played that we don't deserve to be there, or that we've been outplayed, I reckon they're talking from an agenda," he said.
"The only questions I've had from each of our games is about opportunities missed. Now opportunities missed suggests to me that we've got to improve some areas for sure, but it doesn't say that we somehow should think that we don't belong in a competition we've earned the right to be in."
Asked whether Maccabi Haifa beating Juventus, or Club Brugge topping their group shows smaller clubs can punch above their weight, he said: "Look at those clubs historically. Have they always had those results? They haven't, I'll tell you.
"What it means is, the longer you're in this competition, the more opportunities you have to grow and make an impact, but you're not going to go in there for the first time and expect you're going to dominate the most prestigious club competition in the world.
"From our perspective, we felt we've earned the right to be in this competition, we know the areas we've come up short in, but at no stage do I, or any objective observer, believe we've looked out of place."
RB Leipzig's 2-0 win at Celtic Park on Tuesday left Postecoglou's team bottom of their group, four points below Shakhtar Donetsk. The Ukrainian side are well placed to take third place and enter the Europa League in the new year.
Postecoglou said he could not put a timeframe on his side being successful at the elite level, adding: "It's about being at that level and having the chance to play at that level on a consistent basis. That means having to qualify for it and every year you want to grow.
"That's what our objective needs to be, like most clubs our size. If you take away the big five leagues, the clubs that have made an impact at Champions League level are the ones that are consistent qualifiers for it.
"If this was our fifth or sixth year of being in the competition, I'd be having a different discussion.
"It's all about perspective, what you're trying to achieve. This is our first year back in for five years. I'm not going to accept people suggesting that somehow we haven't earned our place or let the game in this country down."