Patrick Kluivert has urged Paris Saint-Germain to learn from the mistakes of their 3-0 loss at Montpellier when they host Ludogorets on Tuesday.
The Ligue 1 champions suffered a third top-flight defeat of the campaign at the weekend, having lost only twice in the whole of last season's title-winning effort.
It left them third in the table and, although Unai Emery's side have already qualified from Champions League Group A, director of football Kluivert has demanded a performance against the Bulgarians.
"Against Montpellier, it was bad," said the Dutchman. "After the game, I said that some players were not at it. But Tuesday night, we will face Ludogorets and it's a very important game for us.
"We have watched the game and we talked about things that were not good. But we must forget all that because Tuesday we have a very important match.
"We should keep what we have done well. It will be another match and we will have a winning mentality.
"We play to win and be first in the group. We realise that this game against Ludodorets can be difficult, but in the Champions League there are no easy games."
PSG lead the group from Arsenal courtesy of a superior head-to-head record, having netted an extra away goal.