Blanc's men went top of the table provisionally ahead of the weekend's fixtures with 11 points from five games, after Blaise Matuidi and Lucas Moura scored for the French champions.
Eight of Blanc's starting 11 at the Stade Jacques Chaban-Delmas had been on international duty of some sort just days earlier.
But his star-studded side came together to earn a valuable three points for their title defence, and Blanc could only joke that his coaching methods were rendered almost pointless after his side played their best football off a poor preparation.
"I think there was a paradox in the preparation for this game," he told BeIn Sport.
"We were not at all prepared for it.
"We try to think of every detail and, ironically, this was our best game since the beginning of the season.
"Players returned yesterday at 6:15pm, nothing was prepared and you see the result? The coach is useless."
Lucas' first goal for PSG in the league came after 1019 minutes on the pitch for the Brazilian, and the winger was thrilled to finally break his duck.
"I needed that goal," he said.
"To prove to others of what I was capable of, but also because I needed a breakout match. I was tired from travelling with Brazil.
"We're still not 100 per cent physically, but we now turn our focus to the first game of Champions League."
