Benteke has been ruled out for at least six months, meaning that the Belgian will miss the remainder of the campaign and this summer's World Cup, and Eris has given details about how the injury occurred at the club's training ground.
Eris told Belgian television station VTM: "He wanted to shoot, and suddenly he heard a noise.
"He thought someone had tackled him from behind. Even people on the centre line heard the sound of the tendon rupture."
Benteke has scored 10 times in 26 appearances in the Premier League this season.