Hazard helps Lille hammer Valenciennes
Lille stay third, in the Champions League qualifying round berth, on 50 points from 28 games. They are seven adrift of second-placed Montpellier with Paris Saint-Germain top of the table on 59 points.
In full view of Manchester City manager Roberto Mancini, who was sat in the crowd, Hazard delivered a brilliant performance and gave the hosts the lead on 18 minutes when he netted from close range after a fine collective move.
Lille doubled their lead in the 57th minute when Benjamin Angoua turned the ball into his own net after a break which Belgium winger Hazard had started.
Aurelien Chedjou and Tulio De Melo then both headed home from Hazard corners to complete the easy victory.
Hazard was a constant threat throughout and could have set up at least two other goals in the first half but goalkeeper Nicolas Penneteau denied Florent Balmont and Mathieu Debuchy shot wide.
"The coach told me before the match," Hazard told French television Canal+ when asked about Mancini's presence.
"I try to be always the same on the pitch, to play my game and show what I am able to do," added the much-hyped Belgian, who was watched by Manchester United boss Sir Alex Ferguson last weekend.
Toulouse climbed up to fourth spot after a Romain Danze own-goal earned them a 1-0 victory at Stade Rennes.
Danze diverted in Emmanuel Riviere's soft shot on the stroke of half-time.
Toulouse trail Lille by three points, while Rennes dropped to seventh on 44 points.
"Since the season began, we have been saying to ourselves that we have a great team. We are more mature, we have been playing together for five years. We grew up," Toulouse midfielder Moussa Sissoko told television channel Foot+.
Edouard Butin and Marvin Martin scored either side of the interval to help hosts Sochaux defeat Nice 2-0 in their relegation clash.
Sochaux went up to 19th on 27 points while Nice stay 18th with the same tally but ahead on goal difference. The pair are two from safety.
Butin volleyed in the opener in first-half stoppage time and Martin added the second when he bent the ball in from outside the box.