Without Falcao, Monaco beaten 3-0 at Metz
Senegalese striker Habib Diallo opened the scoring from the penalty spot when Monaco defender Kamil Glik blocked a shot with his arm. Soon after, Monaco's Ruben Aguilar was sent off for a reckless two-footed challenge.
Diallo made it 2-0 off a loose ball at a free kick, and captain Renaud Cohade added the third with a low shot from the edge of the box.
Monaco gave a start to new signing Wissam Ben Yedder but was again without star striker Radamel Falcao, who is the subject of transfer interest from Turkey's Galatasaray. Monaco said he was injured in training.
Also missing was midfielder Cesc Fabregas, serving the first game of a three-match suspension for appearing to stomp on an opponent's leg last week.
Coming off a 17th-place finish last season which saw it narrowly avoid relegation, Monaco has won just once in 11 league games going back to March.
Last season's runner-up, Lille, lost at Amiens 1-0 after also being reduced to 10 men. Boubakary Soumare was red-carded for a dangerous tackle after a video assistant referee review despite little contact with his opponent. Former Lille player Serhou Guirassy scored the winner for Amiens.
Nice scored two early goals and held on for a 2-1 win over Nimes despite losing defender Racine Koly to a second yellow card early in the second half. That means Nice joins Lyon as the only two teams to have won both their opening games so far.
Nantes and Marseille both stayed winless after a 0-0 draw in which Argentine striker Dario Benedetto blasted a first-half penalty against the crossbar in his first start for Marseille since signing from Boca Juniors. Nantes dominated the second half but some big saves from Marseille captain and goalkeeper Steve Mandanda kept the game goalless.
Of the league's 20 teams, only Marseille, Monaco, and Montpellier have failed to score.