Valenciennes started the match the brighter and the home side found themselves threatening Salvatore Sirigu’s goal on a few occasions early on.
Carlos Sanchez was the first to try his luck from range but his effort swerved just wide of goal. David Ducourtioux then forced Sirigu into a fine stop, the Italian having to get down quickly to tip the full-back’s effort round the post.
France Under-21 defender Nicolas Isimat-Mirin’s flicked header from a corner then forced Sirigu into a punched clearance, as Ancelotti’s side struggled to contain their opponents.
PSG began to assert themselves on the game after 20 minutes and Lavezzi was the first to cause les Atheniens any real scare.
Nicolas Penneteau had only had a couple of ambitious Ibrahimovic free kicks to deal with when the Argentine exchanged a neat one-two with his fellow countryman Javier Pastore and curled an effort just wide of the upright from the edge of the area.
Pastore then wasted a good opportunity to deliver a decent ball into the area when he decided to take aim from a tight angle instead of cutting the ball back, but the visitors took the lead soon after.
Pastore and Jeremy Menez linked well down the right flank and when Menez`s cross was only clawed out to the edge of the area by Penneteau, Lavezzi`s low drive was diverted into the net by Ibrahimovic from close range.
That goal appeared to deflate the home side and the only further action in the opening half was the injury picked up by Alex, which saw him replaced by Mamadou Sakho.
The game as a contest was effectively ended within the opening 10 minutes of the second-half, as Ligue 1’s top goalscorer quickly completed his hat-trick to help PSG to a three-goal lead.
Ibrahimovic’s second came just four minutes after the restart when Pastore’s wicked volley from Rudy Mater’s clearance was palmed straight into the path of the Swede, who made no mistake from six-yards out.
The former Barcelona and AC Milan man then wrapped up his first ever treble in France four minutes later, with his easiest finish of the night.
Lavezzi released Menez into acres of space behind the Valenciennes backline and he drove towards goal and drew out Penneteau, allowing him to square for the unmarked Ibrahimovic to roll the ball into an empty goal.
Menez should have added a fourth when the hat-trick hero tried to repay the favour, but the former Roma midfielder scooped his effort over the bar when his team-mate had unselfishly turned the ball back into his path from six-yards out.
Blaise Matuidi struck the post soon after, but the visitors were not to be denied a fourth as Lavezzi collected substitute Marco Verratti’s pass and turned his marker brilliantly before slotting past a hapless Penneteau.
The win sees Lyon`s lead at the top cut to just two points, while Valenciennes stay in fifth place after their heavy defeat.