Jurgen Klopp has warned Liverpool's top-four rivals there is a lot more to come from his side as they prepare for the return of Premier League action following the World Cup.

Liverpool are sixth in the table, seven points behind Tottenham in fourth following a slow start to the season, but Klopp was encouraged by what he saw from his makeshift side in the 3-2 Carabao Cup defeat against Manchester City on Thursday.

- Stream on ESPN+: LaLiga, Bundesliga, more (U.S.)

"We have left a gap between us and much more exciting positions in the table. We have to chase. I saw good signs last night, I wasn't happy with everything, our counter-press was pretty much non-existent, which I don't like," Klopp said.

"There is a lot to come, we don't think about the break anymore. It's a start for something new and building on the things we've done so far and knowing and expecting that we can do better -- starting on Boxing Day."

Klopp added the next year would be tough for players coming back from the World Cup as he prepared his side for their trip to Aston Villa on Monday.

"For the players who played in the World Cup, the whole year will be incredibly intense," Klopp said. "That's really, really, really tough. We will have to see how we deal with that, and we will be really careful with the information we get.

"That makes planning really difficult for the next game because we were 100% clear what we want to do against City and then you have to change in the last second pretty much, that's not cool but it's the situation and that might happen against Villa as well so we need to be flexible."

Klopp said that midfielder James Milner, who was substituted after 38 minutes of the loss at City due to a hamstring injury, would be out for a couple of games along with forward Roberto Firmino, who is struggling with a calf injury.

"Millie [Milner] didn't get better since then -- he will be out for a couple of games. Same for Bobby [Firmino]," Klopp said.

"Trent [Alexander-Arnold] hopefully will be better. Hasn't taken part in a full session yet."

Klopp added that Alex Oxlade-Chamberlain and Virgil van Dijk are fine ahead of the Villa game.