Divock Origi cancelled out Mounir Obbadi's early opener as second-placed Monaco moved to 63 points with eight games left.
French champions PSG have 73 after beating Lorient 1-0 away on Friday. Lille remained third on 54 points and occupy the Champions League qualifying third round spot, three points ahead of St Etienne who beat Sochaux 3-1 on Sunday.
At Louis II, Monaco started without Joao Moutinho who suffered a groin injury while warming up.
Obbadi replaced him and had an immediate impact as the 30-year-old midfielder opened the scoring after five minutes, latching on to Valere Germain's back pass inside the box.
Jeremy Toulalan, who was back from suspension, came close to doubling Monaco's tally in the 20th minute when his low 20-metre drive went just wide.
Six minutes before halftime Origi tapped in at the far post from Ryan Mendes's cross to put Lille back on level terms.
Dimitar Berbatov, who created two and scored one last weekend for Monaco, fought hard up front but his 69th-minute header went just over the bar.
- Sports & Recreation
- Mounir Obbadi
- Joao Moutinho