Jose Mourinho takes his side to Anfield to conclude the weekend games, hoping to close the gap at the top of the table. United dropped two points against Stoke City before the international break and are in desperate need of three points, as they currently sit six points behind league leaders, Manchester City.
The Merseysiders sit three points ahead of United and a win for them would see Liverpool go level on points with City and Arsenal with 19 points.
Klopp and Mourinho renew their rivalry once more having met on several occasions prior to this clash. The pair were in separate dugouts last year when Liverpool's 3-1 win at Stamford Bridge gave Klopp his first win as manager.
In the corresponding fixture last year, Rooney's late strike gave United three valuable points, and despite his current form which has seen him dropped to the substitute bench for club and country, Klopp still feels the skipper is still a huge threat.
He said: "Rooney is a goal scorer and a threat. A situation like this can happen in a long career. From my side, he's a world-class player."
United can threaten, claims Klopp
Last season's winner from the 30-year-old was just his second goal at Anfield in his career, and the captain is even in danger of being left out of the starting 11 on Monday.
However, even if the skipper is absent from Mourinho's squad, Klopp still believes that United can be a huge problem, due to how strong their squad is.
"Unfortunately this is a really strong side from Manchester, they know about football, they’re experienced, cool in the right moments, they don’t need world-class performances to win a game."
He added: "Even on rainy days, it’s possible to score and win but it doesn’t mean they will win the game. It just means they have a chance."