PSG's 1-1 draw with Guingamp on Saturday opened the door for the men from the principality to reduce the deficit by two points, and the result rarely looked in doubt at Stade Louis II.
Valere Germain found the net four minutes prior to the break to put the hosts ahead with his first top-flight goal for the club.
That lead was doubled in the 57th minute when Emmanuel Riviere beat his marker to fire the ball into the roof of the net from inside the six-yard box.
Lyon stretched their unbeaten run to seven with a 3-0 victory over 10-man Evian, climbing to fifth in the process.
Bafetimbi Gomis opened the scoring in the 19th minute with a low shot from the edge of the penalty area, before John Mensah was show two yellow cards in quick succession to bring a premature end to his involvement.
Alexandre Lacazette took full advantage two minutes before the interval when he found the net with a deft chip.
And the attacker doubled his tally in the 76th minute following a counter-attacking Lyon move to seal all three points.
In the day's remaining match, Bordeaux kept up the pressure on Lyon by recovering from back-to-back defeats to beat Saint-Etienne 2-0 and go sixth.
Abdou Traore's smashed Bordeaux into the lead four minutes prior to the interval, before Carlos Henrique converted from close range six minutes into the second half to make sure of victory.
