The French champions took a significant step towards retaining their Ligue 1 title with a come-from-behind victory at Stade Velodrome.
PSG started the match just two points ahead of third-placed Marseille - and two adrift of Lyon - but they moved back to the summit with an excellent win that came despite Andre-Pierre Gignac's first-half double for the hosts.
Blaise Matuidi scored for PSG in the first half, but they went in 2-1 down at the break, only for Marquinhos to quickly level before Jeremy Morel's own goal settled a thrilling Le Classique.
Both David Luiz and Thiago Motta limped off with hamstring injuries for Blanc's men, though, dampening his enthusiasm ahead of their Champions League quarter-final against Barcelona later this month.
"We will savour the victory but we paid an expensive price because we have lost two players," Blanc said.
"That is a problem - they have muscular problems, which is not very reassuring. It is annoying to have two injured, especially ahead of such a busy period.
"But we are very happy to have won here at Marseille. The players have done a very good job."
Matuidi was simply outstanding for PSG, capping his all-action display with an excellent first-half goal and Blanc was full of praise for the midfielder - who he hopes will add more goals to his game.
The coach continued: "Blaise Matuidi was amazing with his physical game and he worked hard this week to try and score a goal because we were winding him up a bit - he hasn't had much success in front of goal!"