Liverpool go to the City Ground tomorrow night leading the Premier League table.
Slot said this morning: "I have always said you can judge the table best halfway through the season. They are up there with the rest so they are definitely a team in competition with us and the others.
"If you look at the way they play and their results then it is deserved. It is going to be a very difficult challenge for us to get a result.
"They have already showed in retrospect how good of a team they are. When Liverpool lose a home game it’s something you don’t expect. For us to lose on that day was hard to take. Now, looking back and seeing where they are in the league, it is not such a shock result as it felt then.
"They had a good game plan and I expect their wingers, who have done so well, to be in their starting XI tomorrow.
"They have a hard-working team without the ball and they can also hold the ball. Chris Wood is a very good example of that.
"They have scored and been a threat by counter-attacks a lot, but they also have quality when they want to play with the ball.
"Nuno has done a great job at implementing a style of play that suits the players.
"They are a team that hardly concede goals. They don’t take many risks in their build-up play so when they lose the ball they have many players behind the ball and they defend with 11 players."