Ivory Coast striker Gervinho found the back of the net in the 47th and 61st minutes and set up Belgian prodigy Eden Hazard in the 49th.
Lille now have 38 points from 20 games with Paris St Germain, Stade Rennes and Lyon tied for second on 34. Nancy lie 13th on 25 points.
Nancy finished the rescheduled match with 10 men after defender Andre Luiz was sent off for an aggressive tackle on Hazard.
Although Lille were impressive once again, France defender Adil Rami, who is leaving the club to join Valencia at the end of the season, played down title talk.
"There is no message (to our rivals)," he told French TV channel Foot Plus.
"We do our best but it's not like us to talk about title ambitions. Let's remain humble and continue to work hard."
Lille, who have the best attack in the French league, were kept at bay in the first half despite piling on pressure.
Midfielder Yohan Cabaye had a great opportunity to open the scoring five minutes from the break after Florent Balmont won a penalty, but his shot was superbly parried by Nancy keeper Damien Gregorini.
The visitors, however, could not resist a 15-minute blitz after the interval.
Cabaye found Gervinho with a fine defence-splitting pass for the Ivory Coast striker to dribble past Gregorini and score into the empty net.
Two minutes later, Gervinho set up Hazard and the Belgian attacking midfielder found the back of the net with a curling 15-yard shot.
Shortly after the hour, Gervinho put the result beyond doubt, poking the ball home after Gregorini had parried Moussa Sow's attempt from close range.
