The 47-year-old was delighted to see his side put in what he thought to be their best performance of the season despite a supreme lack of preparation time in training
The Ligue 1 champions secured a comfortable win thanks to goals from Blaise Matuidi and and a first in PSG colours for Lucas Moura, despite several first-team stars having only arrived back from international duty at the 11th hour.
And Blanc was amazed by the quality of the performance given the lack of preparation time on the training pitch, suggesting his players had effectively undermined the importance of his own role.
"I think there was a paradox in the preparation for this game," he 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 18:15, nothing was prepared and you see the result? The coach is useless!"
Lucas Moura scored his first goal for the French champions to cap an impressive display on the wing, and the Brazil international admits it was important for him to get off the mark for the club.
"I needed that goal," he said. "To prove to others of what I was capable of, but also because I needed a reference 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."
PSG face Olympiakos on Tuesday in their opening Champions League group game of the season.