Marcelo, who currently plays for Fluminense, was involved in Tuesday’s Copa Libertadores game against Argentinos Jrs in Buenos Aires.
As the match wore on, the former Real Madrid defender attempted to dribble his way past Sanchez but landed awkwardly on the shin of the Argentine.
The incident saw Sanchez immediately dislocate his knee after a poor landing, as he lay on the ground reeling in agony.
Marcelo was sent off for the tackle, and the 35-year-old left the pitch in tears despite not intending to hurt his opponent.
“Today I had a very difficult moment on the pitch,” Marcelo later took to Instagram to express his regret at the incident.
“I unintentionally injured a fellow player. I want to wish him the best possible recovery. All the strength in the world.”
His club Fluminense also sent a goodwill message to Sanchez on Twitter, saying: “Fluminense FC expresses its solidarity and wishes a speedy recovery to Argentinos Juniors defender Luciano Sanchez, who was injured in an accidental move in tonight’s match.”
Meanwhile, Sanchez is expected to be out for close to a year after his horrific injury and is currently on admission at the hospital.