The Reds head into the game looking to preserve their perfect start to the new Premier League season, with the Merseyside outfit currently flying high at the top of the table.
Alisson has been out since August with a calf injury but is now back in full training. Defender Matip missed the wins over Salzburg and Leicester City before the international break due to a knock.
And Salah had to be substituted after being fouled in the closing stages of the 2-1 win over Leicester City last time out.
Klopp was quizzed about the trio and their availability on Friday at his pre-match news conference, but the Reds boss gave little away heading into the crunch clash.
Speaking in an interview quoted by Liverpool FC’s website, Klopp said: “Better – how good, we have to see, that’s the truth.
“There are two more sessions to come from this afternoon and we have to see. Then we’ll make decisions, that’s how it is. Nothing is fixed.
“The players on international duty all came back healthy, which is very, very important, so we now had three or four days with the full squad to prepare it, which is a little bit comfortable at least.”
Liverpool FC have won all eight of their Premier League games this season, while Manchester United have managed just two victories from their opening eight clashes.
The Merseyside outfit won the Champions League last season thanks to a 2-0 victory over Tottenham Hotspur in the final back in May.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news