Trent Alexander-Arnold described Manchester City's recent slump as a "big surprise" but warned against ruling Pep Guardiola's men out of the Premier League title race.
Guardiola is presiding over the worst run of results in his managerial career, with City having won just one of its last 10 matches in all competitions.
Liverpool holds an eight-point lead over City and also has a game in hand, but Alexander-Arnold is well aware that the champions have a habit of coming on strong after Christmas.
Speaking to Sky Sports, he said: "I think it [City's loss of form] is a big surprise to everyone. I've always said that if you've ever got a chance to beat City, it's always before Christmas. I think maybe they're still finding their feet in the first three, four months of the season. And then after Christmas going into New Year, at that point you can forget about beating them.
"You can honestly forget about it because not many teams do. Once they hit their stride, once it clicks around the new year, they'll go five months without losing a game and they might draw one or two. But they'll just win and just carry on winning. So I wouldn't be surprised if that was the case again.
"They probably have dropped more points than they probably ever have (in recent times) so far this season, but they're a team that have four in a row, won a treble. They are incredibly strong with world-class players and an incredible manager as well, of course. You can never rule them out and I wouldn't be surprised if they're back in the title race come the end of the season."
Liverpool underlined its credentials both domestically and in Europe in recent weeks with dominant 2-0 victories over both Real Madrid and City, and Alexander-Arnold talked up the importance of both of those results.
"I think that was just a statement week for the team, for the club," he said. "Probably they are our two biggest rivals in Europe and domestically over the last five or six years. I guess we've struggled to overcome them as a team. So to beat them both in the space of a few days was something that really sent a statement to everyone that we're a real team.
"And whether they wanted to believe it before that or they don't believe it still, it doesn't bother us. We know what level we are. What others want to think about us doesn't affect us. We know the quality we've got. We know what levels we can hit. We know we've still got a lot to improve and we will, and we'll get better throughout the season, which I think is good for us and bad for anyone else."