The Red Devils remain undefeated this season, with their Premier League record reading six wins and one draw in seven matches.
Jose Mourinho's side, joint leaders on 19 points from seven games with Manchester City, will hope to continue that momentum in what will be their biggest test of the season to date.
Two goals from Juan Mata piled misery onto Liverpool, and United ran out 2-1 victors.
Coutinho and Firmino have now returned to Melwood to reconvene with the rest of the squad as Liverpool prepare for the early Saturday kickoff against Manchester United at Anfield.
And Klopp can cling to the fact that his side have lost just once to a top-six side directly after an international break.
"We always fight in each game, but this game is a big game and can make a difference for us".
Liverpool's' recent form is worrisome. "We just trust the players that are going to help".
"We have to improve our place in the table".
West Ham boss Slaven Bilic has leapfrogged Everton's Ronald Koeman as favourite to be the next managerial casualty after his side's woeful start.
However, Liverpool have produced some impressive displays this season, including their brilliant performance in the 4-0 victory over Arsenal back in August.
"They played (Emre) Can and (Jordan) Henderson for some reason and they did that for 90 minutes when they normally project more players in attack", Mourinho said afterwards.
Salah was disappointed to hear that team-mate Saido Mane has been ruled out for six weeks while on international duty and will miss this weekend's tie. "They were very cautious". Leading scorer Romelu Lukaku has scored five times against Liverpool in the past but has only won two of his 13 meetings with the Merseysiders. United are different. "This is the way we have to play big matches", Ander Herrera said last October.