Lille lead the standings on 28 points, one ahead of Paris Saint-Germain who went second after a 3-1 victory over Stade Brest. Stade Rennes complete the top three, level with PSG.
Olympique Marseille, who topped the standings coming into the weekend, slipped to fourth on 26 points after a goal in stoppage-time condemned them to a 1-0 defeat at Nice.
Lyon roared back into the title race on Saturday, surging up to fifth courtesy of a dramatic 2-1 win at Montpellier. Lyon are only two points off the pace after their worst start to the season in 10 years.
At Lille, Sow took his tally to 13 league goals this season by scoring at the beginning of each half and completing his hat-trick 10 minutes from time.
He also had a hand in Maxime Baca's own goal before strikers Gervinho and Pierre-Alain Frau added gloss to the hosts' brilliant display with second-half goals.
ANGRY AND DISAPPOINTED
Lorient's Kevin Gameiro scored twice and Lynel Kitambala added another but the visitors collapsed after goalkeeper Fabien Audard was sent off in the 85th minute.
"I keep saying it does not matter if I concede two or three goals provided we score more," Lille goalkeeper Mickael Landreau told French TV channel Foot Plus.
"We will talk about the title later on. For the moment we are just enjoying our victory. I think a group will break away from the rest of the peloton and we have to be consistent."
Champions Marseille dominated their match at Nice but failed to convert their chances as the hosts defended stoutly and secured the points through Emerse Fae two minutes into added time.
"It is hard," Marseille defender Taye Taiwo said. "We defended well. We got some chances. They were very lucky. We are angry because we did not get the three points.
"It is a big disappointment considering the quality of the match," coach Didier Deschamps added. "We will have to digest this defeat. We know the road is still long."
At the Parc des Princes, Nene volleyed home early in the game against Paris Saint-Germain.
Brest equalised after the interval through Nolan Roux but PSG swiftly responded through Mathieu Bodmer and Ludovic Giuly secured the points 15 minutes from time with a volley set up by Guillaume Hoarau.
Elsewhere, Girondins Bordeaux salvaged a point from their visit to Saint Etienne with a 2-2 draw.
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