Blanc has hailed his opponents' performance on the night but was delighted with his team's resolve at the Stade de la Beaujoire.
"Everyone expected this victory," Blanc told reporters after the game.
"It was difficult because Nantes played a beautiful game. Certain situations should have been better managed, we did not do that, we have suffered up to the last second."
Former France manager Blanc admitted that it had not been a great performance from PSG, but stressed that a lack of match preparation is affecting his team's displays.
"I knew before the game that the rapport may not be perfect," he added.
"We are behind many teams in terms of preparation.
"We could revise this 4-4-2 but we have to find a plan with a good balance. We have an interesting attacking potential, but matches are also won at the back and we conceded goals every time.
"There is a balance to be struck. We had too bad a start to the second half."