Coming into this clash in the bottom two and one point adrift of safety, St-Etienne were desperate for a positive result against high-flying Monaco.
Their current run of two games unbeaten at home, coupled with Monaco’s one away win in 10, may have given them hope, but they were dealt an almost immediate blow as they conceded an early opener.
A quick Monaco move ended with Maghnes Akliouche tapping home Caio Henrique’s delivery, giving the hosts a mountain climb.
Akliouche had another opportunity later on in the half to double his side’s advantage, while Gautier Larsonneur made a comfortable save from Jordan Teze.
Yet, while Les Monegasques often found themselves in dangerous positions, Larsonneur was rarely troubled.
Les Verts, meanwhile, could have equalised through Irvin Cardona, but his delicate chip over Philipp Kohn went narrowly wide of the post.
Despite entering the break a goal down, the home team threatened sporadically, suggesting they could cause problems after the break.
That ultimately proved to be the case, as after substitute Breel Embolo headed into the ground and over from close range, St-Étienne found an equaliser.
Zuriko Davatashvili had wasted a fantastic opportunity by going for goal himself when Ibrahima Wadji was unmarked and with a free shot on goal, but he atoned for his selfishness with a stunning strike, curling into the top corner from outside the area.
Monaco were in no mood to drop points in their quest for UEFA Champions League qualification, and they were soon back in front through Al-Musrati’s deflected attempt less than three minutes later - his first goal in the French top flight.
With around a quarter-hour left on the clock, Monaco assured the points via Folarin Balogun’s cool finish.
In response, Saint-Etienne pushed forward, but they were unable to recover and remain one point adrift of the relegation play-off spot and three from automatic safety.
Meanwhile, Monaco climbed back into the top three and the UEFA Champions League qualification places thanks to just a second win in five league outings.
Flashscore Man of the Match: Zuriko Davitashvili (Saint-Etienne)