Zlatan Ibrahimovic was the PSG hero again on Sunday as he scored both goals in a 2-0 win over Saint-Etienne at Parc des Princes.
That victory extended the champions' winning run to seven matches in all competitions and maintained their eight-point lead over Monaco at the summit with nine games remaining.
Matuidi believes only a PSG collapse can stop them defending their title.
"We are league leaders in front of Monaco. When we lead, we try not to look back. We remain focused on what we do best," he said.
"Now it is only us who can make us lose the trophy. (Sunday was) a big step forward, it is a big result for us.
"Nothing is done yet though. It is up to us to remain focused in order to keep up this pace.
"We have to try to finish the season well with a title. We will do everything in our power to remain at the top of the table."
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