The England striker, who missed most of last season with a left knee problem — picked up the latest injury after coming on as a substitute in last week’s 2-1 victory over Spurs in the EFL Cup.
Liverpool manager Jurgen Klopp said he was devastated for Ings, who joined the Reds for £6.5million plus £1.5m based on performance related factors last season.
“To say we are gutted would be an understatement,” Klopp told club website. “He is such a great boy and has worked so hard that he deserves better luck than this.
“It is typical of Danny’s personality, on and off the pitch, that he picked up this injury to his knee when courageously trying to win the ball back for his team by making a tackle.”
Klopp said Ings, who won his only cap in a Euro 2016 qualifier against Lithuania with injury ruling him out of contention for a place at the finals, has shown strong character, believes he will bounce back strong.
“It is this same personality that means he will come back as good and as strong from this latest setback as he has done in the past,” said Klopp. “I’m told the likely lay-off is anywhere from between seven to nine months.
“He is mentally strong, physically strong and will have the very best treatment and rehab possible to make sure when he returns he is ready to play for us at the level we know he is capable of.”