The injury occurred right at the end of the match, when Salisu went down clutching his knee and required medical attention.
Subsequent examinations confirmed the severity of the problem, ruling the centre-back out for an extended period.
In a statement, AS Monaco confirmed the diagnosis and pledged their support to the player throughout his recovery.
“At the very end of the match against Olympique Lyonnais, our centre-back Mohammed Salisu suffered an injury to his left knee,” the club said.
“Medical examinations revealed a torn anterior cruciate ligament. The Club will support Mohammed throughout his recovery and is behind him all the way.”
An ACL tear typically sidelines players for around nine months, a timeline that all but rules Salisu out of Ghana’s plans for the upcoming World Cup.
The injury is a significant blow for both club and country, with the 25-year-old having been a key figure in Monaco’s defence and an important option for the Black Stars.
Since his debut for the national team in 2022, the 26-year-old has scored four goals in 22 games.
Salisu’s setback also adds to a growing list of Ghanaian internationals who have suffered similar injuries over the past year.
Fatawu Issahaku, Tariq Lamptey, Alidu Seidu, Ernest Nuamah, Abdul Mumin and Baba Iddrisu have all been sidelined by ACL tears, raising concerns about the impact of such injuries on Ghana’s player pool at both club and international levels.
For Salisu, attention now turns to surgery and rehabilitation, with the immediate focus on recovery as he begins a long road back to full fitness, hoping to return stronger after a frustrating and cruel setback.
