Matuidi - who had some responsibility for both of the goals conceded - underlined the importance of concentrating on the Champions League clash against Dinamo Kiev coming up on Wednesday.
Speaking to lemeilleurdupsg.fr, Matuidi said: “We are very disappointed to lose at home with 11 men against nine. We need to ask questions of ourselves to find out the problem and then we need to get back to work.”
As one of the outstanding players for PSG this season, the 25-year-old is keen to show his continued determination for improvement.
“We don’t have time to reflect because we have a match on Wednesday,” he added.
Coach Carlo Ancelotti alluded to the possibility that he may make changes to freshen things up in the side.
He said: “This is a tough time. During the next few games, we will have to change some things, in our attitude, and in our play.”