Despite the loss of several key players during the offseason, Lyon defended well and played as a compact bloc while Monaco, the 2017 champion which narrowly avoided relegation last season, lacked inspiration and did not create a single dangerous move.
After qualifying for the Champions League last season, Lyon introduced a new coaching setup of sporting director Juninho and coach Sylvinho, who replaced Bruno Genesio.
Moussa Dembele put the visitors ahead after five minutes when he jumped higher than Kamil Glik and Jemerson to unleash a thumping header into the top right corner from a well-taken corner kick by Bertrand Traore.
Monaco's hopes of pulling one back took a blow after 30 minutes when Cesc Fabregas was sent off following a clumsy move. Trying to stop Leo Dubois' run to the goal, Fabregas stomped on the defender's left calf. Referee Ruddy Buquet initially gave a yellow card to the former Arsenal star but changed his decision to a red after consulting the video-assistant referee system.
Left unmarked outside the box, Memphis Depay made it 2-0 six minutes later with a fine strike that left new Monaco goalkeeper Benjamin Lecomte confused as the ball went through his legs.
Lecomte, who joined from Montpellier during the offseason, made amends with a couple of good saves after halftime as Lyon kept dominating. But the France international was powerless in the 80th minute when Thiago Mendes provided the assist with a cut-back pass to Lucas Tousart, who converted it with a powerful low shot.
Paris Saint-Germain starts the defense of its title on Sunday at the Parc des Princes against Nimes.