Laurent Blanc's men cruised into the quarter-finals of France's oldest competition on Wednesday, thanks to first-half goals from Edinson Cavani and Yohan Cabaye.
Nantes never threatened a comeback as PSG eased into the last eight and - ahead of Saturday's Ligue 1 meeting with Caen and next Tuesday's UEFA Champions League last 16 first leg clash with Chelsea - Matuidi feels teams are once again scared of a PSG side that proved inconsistent in the first half of the season.
"We are committed in four competitions," Matuidi told France 3. "It has gone rather well since January.
"We have a very good staff and a very good team. It is difficult to play PSG, teams fear us a little more because we have found our game and we are winning."
However, PSG - who have already reached the final of the Coupe de la Ligue - face a tough test in the last eight having been handed a home tie against Monaco in the quarter-finals.
Holders Guingamp will visit fourth-tier Concarneau, while Saint-Etienne travel to Championnat National side Boulogne.
The winners of Thursday's game between Metz and Brest will take on Ligue 2 Auxerre. The quarter-final ties will be played on March 3 and 4.
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