Ange Postecoglou has urged his Celtic side to come out swinging after they were floored by Norwegian champions Bodo/Glimt on Thursday night.
The Hoops take on Dundee at Parkhead tomorrow, having surrendered a 17-match unbeaten run in the Europa Conference League.
Celtic were humbled 3-1 by their opposition, with goals from Runar Espejord, Amahl Pellegrino and Hugo Vetlesen leaving them on the canvas - despite a strike from Daizen Maeda halving the deficit at one stage.
However, Postecoglou won't let his players feel sorry for themselves after the loss and said it's now time for them to bounce back off the ropes.
He said: "You have got to take a punch like you're a good boxer and show: 'OK, it happens to the best'.
"We can't feel sorry for ourselves. Ultimately, this is part of football. You have got to take the knocks. It is not just about feeling good and going around beating teams.
"We have just got to dust ourselves off, not feel sorry for ourselves.
"The next challenge is Sunday, that is our focus.
"We want to continue our good form in the league and Sunday is an opportunity to do that.
"Every challenge is a new one. This is another one for us. It is the first game we have lost in quite a while and how we react to it is obviously going to be important. We'll see.
"So far this season we've reacted to challenges really well.
"But it's another one and we have to show the right kind of reaction."
The squad will train today ahead of their match against Mark McGhee's Dundee tomorrow.
However, Postecoglou wouldn't be drawn on whether he will make wholesale changes in response to the defeat.
He added: "Look, we’ll prepare the same way we always have, give them the feedback they need and the rest is up to them, as it has been all along.
"So far this season they’ve shown they’re a really resilient group of players. I expect to see that on Sunday.
"It depends. The most important thing is we get the team right for Sunday and then we'll have a look at Thursday."
