Former Italy international Grosso, 46, oversaw just one win in seven matches since taking over as coach from Laurent Blanc on September 16, and leaves with Lyon three points adrift at the foot of the table.
The club said in a statement the decision to move on from Grosso was driven by the poor run of results and came following an "in-depth analysis of the first-team situation".
Sage, 44, previously coached Lyon's under-16s in 2019 before joining French third-division side Red Star.
Until last season he served as coach Habib Beye's assistant prior to returning to Lyon, where he oversaw the club's academy.
"I take things on a day-to-day basis. We'll do everything we can to keep things moving in the right direction. Everything is being done in a hurry, of course," Sage said during a press conference Thursday.
Saturday's match against Lens will make Sage Lyon's fourth coach of a turbulent 2023-24 season, including Jean-Francois Vulliez's interim stint between Blanc and Grosso.
Lyon have just seven points from 12 games and relegation is starting to seem a genuine prospect for the club that won seven consecutive titles between 2001 and 2008.
The side's troubles have gone beyond the pitch this term, and Grosso was injured last month when Lyon's team bus was stoned on its way to a game at Marseille, leaving him with cuts to the face that required stitches.
Самый милый и жестокий шутер-рогалик AK-xolotl перенесли на Android
This underwater city builder had me more emotionally invested in my corals than SimCity does in my human citizens, and you can try it at the next Steam Next Fest
Elden Ring Nightreign Equilibrious Beast boss guide: How to beat Libra
The Kingmakers system requirements show that the hardest part of running the game may be finding 80 GB free for the install
Жаркое, дождливое и опасное: какое лето ждет россиян
Архангельские гребцы завоевали две медали на первенстве России в Краснодаре
Арктика с женским лицом: Архангельск готовится к масштабному форуму лидеров и идей
Заместитель прокурора Архангельской области и Ненецкого автономного округа Павел Матанцев провел личный прием работников ГУП НАО «Нарьян-Марская электростанция»
СЛЕДЫ НЕЙРО ИИ: СЕНСАЦИЯ В ДЕЛЕ ГРУППЫ ДЯТЛОВА: США И СССР ПОДГОТОВИЛИ СНОС...США. ОГРОМНЫЙ ПОЛИТИЧЕСКИЙ СКАНДАЛ. Новости! Россия, США, Европа могут улучшить отношения и здоровье общества?!
Московские врачи ждут на вокзале пассажиров с поезда, сошедшего с рельсов
Региональные власти разрешили устанавливать штрафы за шум до 80 тысяч рублей
Севастополь снова встречает детский благотворительный фестиваль «Добрая волна»
