London - Liverpool forward Sadio Mane could be out of action for up to six weeks after picking up a hamstring injury on international duty, the club said on Tuesday.
A statement on the club's website said he was substituted just before the end of Senegal's 2-0 World Cup qualifying win over the Cape Verde Islands on Saturday.
"It has now been confirmed that he picked up an injury during that fixture that could keep him out of action for up to six weeks," the statement said.
Mane's absence is a huge blow for Liverpool boss Jurgen Klopp after the forward scored three goals in four Premier League appearances this season.
The injury is especially badly timed for Klopp with Liverpool's bitter rivals Manchester United visiting Anfield on Saturday.
Liverpool are already seven points behind United in the Premier League and can't afford to drop points against Jose Mourinho's in-form United.
Sane's value to Liverpool has been immense since his move from Southampton in 2016, but he has struggled to stay fit.
He scored 13 Premier League goals last season despite missing the whole of January due to the Africa Cup of Nations.
Liverpool won just once in seven matches in all competitions during his time away with Senegal.
Mane tore the meniscus in a knee during April's Merseyside derby against Everton which prematurely ended his season and required surgery.
They coped better that time, with five wins, two draws and a defeat.
Having worked hard to get back to fitness this term, Mane was sent off at Manchester City on September 9, resulting in a three-match ban.
Since his debut in August 2016 Liverpool average 2.2 Premier League goals with Mane in the team, compared to 1.6 goals in his absence.
Klopp has signed Mohamed Salah and Alex Oxlade-Chamberlain since the end of last season to add more depth to his attacking options.
Egypt winger Salah has scored six in 11 games this season, making him the club's leading scorer, but former Arsenal midfielder Oxlade-Chamberlain has been less impressive so far.