Lyon kept pace with Lille, who won 3-2 at Nimes earlier despite playing much of the match with 10 men.
Lille are three points ahead of Lyon, who have a game in hand, and five ahead of Montpellier, who did not play for a second consecutive week, and have played two fewer matches.
The French title race is all but over with reigning champions Paris Saint-Germain 10 points clear, but a young Lille side are eyeing a return to the Champions League group stage for the first time since 2012, while Lyon, who squeaked into the last 16 in Europe in midweek, are seeking to ensure they will be back next year.
“This match was one of our most dominant performances in the league,” said Lyon coach Bruno Genesio. “Even with superiority, we continued to play simply, to work for each other.”
Lyon took the lead in only the sixth minute with a goal by Houssem Aouar, his sixth of the season.
Nabil Fekir added the second in the 34th minute. Kenny Tete shrugged off a timid challenge to pull back a low cross which Fekir attacked while Monaco’s Jemerson hesitated.
Monaco managed only one shot all game. They played almost the whole second half with 10 men after Aleksandr Golovin raked his studs down the back of Fekir’s calf in the 47th minute and was sent off.
– ‘Childish attitudes’ –
Ferland Mendy added a deserved third for Lyon just before the hour mark.
“The match in Kiev on Wednesday made us realise that we had a strong group,” said Genesio. “And that we had to stop the childish attitudes that we have seen on some matches.”
Monaco, the only team in the bottom half of the French league table to play this weekend, meekly wasted a chance to gain ground on their rivals.
“We have to look at the first goal we conceded and especially the second goal which summed up this game,” Henry said. “Winning without desire is hard.
“We have to try to put this game behind us, we have a big game against Guingamp next week.”
Earlier, in-form striker Nicolas Pepe scored what proved to be the winner as 10-man Lille won at Nimes.
“What a match, I’m really proud of my players,” said Lille coach Christophe Galtier. “We must not forget that we played for more than an hour and 20 minutes with 10 men.
“With the added time, it was a very long and hard match physically.”
Portuguese teenager Rafael Leao headed Lille into a fourth-minute lead, but Galtier’s men suffered a setback when former Southampton centre-back Jose Fonte was sent off in the 16th minute.
Jonathan Bamba’s deflected effort doubled the advantage shortly before the interval, though, and Pepe appeared to have made the points safe midway through the second half with his 12th goal of the campaign.
“After the PSG strikers, Pepe and Bamba are the best,” said Nimes coach Bernard Blaquart.
The 10 men finally started to tire late on, but Lille held on for victory despite Nimes goals from Rachid Alioui and Clement Depres.