With PSG's main title rivals facing tough tests this weekend, PSG could move to the top of the table with a win over ninth-placed Montpellier on Saturday.
Marseille lead the French top flight with 38 points, one ahead of PSG, while Lyon are third on 36 ahead of the final round of the season before the winter break.
Having lost their previous two games in all competitions to Barcelona and Guingamp, PSG came from behind on Wednesday to defeat Ajaccio and advance to the quarter-finals of the Coupe de la Ligue with Edinson Cavani, Serge Aurier and Jean-Christophe Bahebeck scoring for Blanc's men.
"After two defeats in five days, it's a good thing to have fought back," Blanc said after the match.
"I think we could have scored more goals this evening but Ajaccio gave it their best shot so congratulations to them."
Both Marseille and PSG missed the opportunity to gain an advantage on the other last week with Guingamp stunning the reigning champions 1-0, while Marcelo Bielsa's leaders went down by the same scoreline at Monaco.
The Uruguayan striker has done well in Ibrahimovic's absence and is PSG's leading scorer in all competitions.
Rolland Courbis' side gave up a two-goal lead in their 3-3 draw with Lens last week, while they have lost three of four matches against the top five teams so far this season.
Montpellier's one win against the leading contenders came in round two when they stunned Marseille 2-0.
