Matuidi came off the bench to score the only goal of the game past Jesper Hansen in the 89th minute at the Parc des Princes on Wednesday, after PSG had struggled to gain a foothold in the game.
And while Blanc conceded that his side were far from their best against the Ligue 1 strugglers - who played the last 30 minutes with 10 men after Kassim Abdallah was sent off for a second bookable offence - he was grateful for Matuidi's late intervention.
"It is no coincidence that Matuidi broke the deadlock," Blanc was quoted as saying by L'Equipe.
"He always believes and he always gives everything."
PSG are now 10 points clear at the summit and will retain the title if they beat Sochaux on Sunday.
They could be confirmed as champions even sooner if Monaco lose at Ajaccio on Saturday.
However, Blanc has warned his side that they can take nothing for granted and must improve at Sochaux.
He added: "The first period was very bad. We did not attack the game with the right mindset.
"There was little motivation. There was little movement, little marking on set pieces. Evian might even (have) led.
"It will be (better against Sochaux) because otherwise we will have the same kind of difficulty."
