Emmanuel Riviere came off the bench to score his fifth goal in four games as big-spending Monaco underlined their title ambitions by climbing to the top of Ligue 1 with a 2-1 victory at Olympique Marseille on Sunday.
Riviere secured the win in the 79th minute as unbeaten Monaco leapfrogged Marseille to the top of the standings with 10 points from four games. Marseille and St Etienne have nine.
Summer signing Radamel Falcao had earlier cancelled out Lucas Mendes' 43rd minute opener for Marseille from a corner kick.
The Colombia striker tapped home a Layvin Kurzawa cross before being replaced by Riviere after suffering a suspected thigh injury.
Riviere's pace offered deeper solutions to midfielder Joao Moutinho, another high-profile summer catch, who was making his Ligue 1 debut.
The Portuguese set up the forward who shot past goalkeeper Steve Mandanda to seal the victory.
In the day's early kickoff, St Etienne defeated Girondins Bordeaux 2-1, trailing Marseille on goal difference.
Champions Paris St Germain are fourth, one point behind, after beating promoted-side Guingamp thanks to two injury-time goals by Adrien Rabiot and Zlatan Ibrahimovic.