Monaco regained second spot in Ligue 1 courtesy of a 2-0 win at mid-table Lorient on Sunday.
Goals in the second half from Thomas Lemar and Joao Moutinho secured the three points required by Leonardo Jardim's men to climb above Angers, who were beaten by Nice on Friday night.
Lemar's thumping effort on 53 minutes was adjudged to have crossed the line after rebounding down off the crossbar, while Moutinho found the net four minutes later with a superbly-executed free-kick.
The victory was Monaco's sixth away from home this season, but they still remain 21 points adrift of runaway leaders Paris Saint-Germain.
Michy Batshuayi, Georges-Kevin N'Koudou and Bouna Sarr all scored for the visitors at Stade Michel-d'Ornano, with Ronny Rodelin replying for the hosts.
St Etienne's 1-0 derby victory over Lyon saw them leapfrog their opponents and climb to within a point of the top four.
