Argentine winger Di Maria scored before the break to lift PSG, who were without the injured Neymar and Thiago Motta, on to 53 points from 20 games.
Monaco are second on 42 points after a goalless draw at Montpellier on Saturday with third-placed Olympique Lyonnais behind on goal difference after a 1-1 home draw against Angers.
Claudio Ranieri's Nantes, who finished with 10 men against PSG after Diego Carlos received a second yellow card in the last minute, stayed fifth on 33 points.
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PSG enjoyed most of the possession and were quickly ahead as Di Maria scored from inside the box after collecting a low cross from Edinson Cavani in the 12th minute.
Di Maria went close to doubling the lead eight minutes before the interval but his shot from close range hit the bar.
Nantes had a good chance early in the second half but Alphone Areola made a fine save to deny Emiliano Sala.
Earlier, Lyon's Nabil Fekir cancelled out Karl Toko Ekambi's opener from the spot for Angers as the hosts missed out on the opportunity to take second place.
Angers finished with 10 men when Flavien Tait was sent off for a second bookable offence six minutes from time.
Angers took the lead in the 14th minute when Toko Ekambi wrong-footed Anthony Lopes from the penalty spot after Angelo Fulgini had been fouled in the box.
Lyon equalised two minutes into the second half as Fekir found the back of the net with a fine curled shot from Maxwel Cornet's cross.
The home side had the best chance to add another goal in the 70th minute when Memphis Depay beat Ludovic Butelle with a header, only for defender Romain Thomas to clear the ball off the line.
(Reporting by Julien Pretot,; Editing by Ed Osmond)
