Naby Keita and Thiago Alcantara are set to miss several games for Liverpool.
Keita was substituted at the midway point of Tuesday’s comprehensive Carabao Cup third round victory over Norwich City with a foot problem.
The issue is the latest that the Guinean midfielder has faced in his first three years at Anfield, leading him to miss a combined 53 games during that time.
Jurgen Klopp confirmed on Friday that Keita will be sidelined for the Reds’ trip to Brentford in addition to a Champions League group encounter with Porto.
He said: “It’s nothing really serious, but it keeps him out of the next game for sure – and maybe a little bit longer, we have to see.
“It’s nothing serious but it’s obviously painful and we have to see how we can deal with it.
“Of course it’s not cool when players have had a good pre-season, could play a lot of games and now are out.
“That happens throughout a season and hopefully when they come back then that’s it and they can play the rest of the season, that would be extremely helpful.”
Thiago Alcantara is set to join Keita on the sidelines after pulling up with a calf injury during Liverpool’s home victory over Crystal Palace last weekend.
Klopp does not anticipate the former Bayern Munich playmaker being available until after the October international break at the earliest.
“It’s not 100 per cent clear when Thiago will be back,” added the Liverpool manager.
“It’s a muscle in the calf issue, so after the international break probably.
“I don’t think there’s anything earlier possible. We will have to see.”