Lille leapfrogged Paris Saint-Germain to grab the lead in Ligue 1 on Saturday after Jonathan David found the back of the net in a 1-0 win over the French champions, who had Neymar sent off in the last minute.
Canada striker David scored in the first half to put the northerners on 66 points with seven games remaining, three ahead of PSG who were lacklustre throughout the showdown.
Neymar was sent off when he picked up a second yellow card for shoving Tiago Djalo, who reacted with a foul-mouthed rant and was also shown a red card.
Monaco moved up to third on 62 points with a 4-0 thrashing of promoted Metz.
Olympique Lyonnais, fourth on 60 points, take on fifth-placed RC Lens later on Saturday.
PSG have won seven of the last eight Ligue 1 titles, only finishing second behind Monaco in 2017, while Lille are looking to claim their first since 2011.
Lille, who were without Yusuf Yazici after the Turkey midfielder tested positive for COVID-19, defended thoroughly throughout and were the sharper side at the Parc des Princes to bag a deserved three points after two consecutive defeats in competitive matches.
PSG, who travel to Bayern Munich for their Champions League quarter-finals first leg on Wednesday, have now lost their last three home games in Ligue 1.
Neymar, in his first Ligue 1 start in over two months, found Kylian Mbappe early on with a defence-splitting pass, only for the French striker to see his low crossed shot parried away by Mike Maignan.
Lille went ahead on 20 minutes as David fired under the roof of the net from Jonathan Ikone's cross after controlling the ball with a soft touch.
PSG struggled to create chances despite enjoying most of the possession and Lille threatened several times with lighting-quick counter attacks.
Neymar forced Maignan to a good save with a powerful half volley from just outside the box on the hour and he came close again in the 70th with a diving header that went just wide.
The Brazilian will, however, miss PSG's next league game against Racing Strasbourg following his sending-off.
Coach Niko Kovac refused to get carried away, though.
"There are still 21 points at stake and we first need to secure fourth place," he told a news conference.
"But we're good. We have a good momentum."