The 47-year-old German arrived at the Parc des Princes on a two-year contract in 2018, and guided the Parisians to their first-ever Champions League final last season.
Milan's revival is real, as they spent the international break on top of Serie A, unbeaten and two points ahead of Sassuolo in second.
Paris coach Thomas Tuchel made six changes to his line-up following the 2-0 midweek win at Istanbul Basaksehir in the Champions League.
Both PSG and Lille have 18 points from eight games but PSG is top with the better goal difference.
Despite bringing in new players, Lille managed to grind out wins under coach Christophe Galtier, raising hopes of a first league title since coach Rudi Garcia's double-winning side in 2011.
Mbappe gave PSG the lead after he was played through by Rafinha, rounding the advancing Reynet before slotting in his third league goal of the campaign.
Mauro Icardi scored both the goals in the match in the ninth and 62nd minutes respectively. PSG will now take on Angers on October 3.
It was a second successive French league win for PSG who began the season still smarting from defeat in the Champions League final.
The Brazilian, along with the likes of Kylian Mbappe, Angel Di Maria and Leandro Paredes, were all quarantined, with Neymar making his return to training on Friday.
The Dutch striker on Friday levelled the score from a penalty in the 39th minute after Aurelien Scheidler set up an early lead for the visitors just 14 minutes into the game
PSG had been scheduled to play at Lens on Saturday evening but the French league postponed the game to Sept. 10 at the defending champion's request.
Amiens were relegated from Ligue 1 as the second-bottom team after the final table was decided based on points per game, with 10 scheduled rounds of matches remaining.
Fabregas stated he understands why the decision was taken but also pointed towards other leagues trying to finish their respective seasons.
Marseille were second in the French Ligue 1 when the season was suspended in mid-March with 10 games remaining.
PSG led the table by 12 points from Marseille when the season was suspended in mid-March because of the coronavirus outbreak, which has gone on to kill more than 24,000 people in France.