The Egyptian FA confirmed on Wednesday that Mohamed Salah has again tested positive for coronavirus.
The news will come as a blow to reigning Premier League champions Liverpool as it means their key attacker will miss Sunday's clash with table-topping Leicester City.
Salah, who is the joint leading scorer in the English top-flight with eight goals, could also be ruled out of the Champions League match with Atalanta at Anfield next Wednesday and the following weekend's trip to Brighton.
The EFA confirmed that Salah, said to be showing only mild symptoms, had been tested again on Wednesday and that the result was positive.
Salah tested positive for Covid-19 on Friday and went into isolation which meant he missed Egypt's African Cup of Nations double-header against Togo.
The news of Salah's first positive test came after he reportedly attended his brother's wedding, with footage posted on social media appearing to show him dancing with other guests.
On Tuesday, the 28-year-old thanked supporters on social media for their messages of goodwill and assured them that he will "be back on the field soon".
The previous day, it was announced that Salah's fellow Egyptian intentional – and Arsenal midfielder – Mohamed Elneny had contracted the virus and was also self-isolating.
Elneny, who played in Egypt's 1-0 home win over Togo on Saturday, is set to miss the Gunners' Premier League fixture at Leeds United on Sunday after also testing positive for a second time. He is said to be asymptomatic
And Arsenal suffered a second blow when the Bosnia and Herzegovina Football Federation confirmed that defender Sead Kolasinac has tested positive for Covid.
The 27-year-old played in the 3-1 Nations League defeat in the Netherlands on Sunday but is now self-isolating and will not be involved in the match against Italy on Wednesday night.
Liverpool were already dealing with an injury crisis before Salah's positive test last week. Key centre-half Virgil van Dijk is already set to miss most of the season after undergoing knee surgery, while manager Jurgen Klopp is also without Trent Alexander-Arnold, Joe Gomez and Joel Matip.
Andy Robertson, Fabinho, Thiago and Jordan Henderson are all doubtful for Sunday's game at Anfield.