The most worrying problems are the ones that creep up almost unannounced. And such is the case for Liverpool and their slightly porous rearguard at present.

Lucas Bergvall's controversial winner for Tottenham Hotspur in their League Cup semi-final first leg on Wednesday evening means the Reds have now kept a clean sheet in only two of their last nine games in all competitions.

It's in stark contrast to the start of the season, when the arrival of Arne Slot prompted a mean streak that saw his team shut out the opposition in six of his opening 10 games in charge.

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And before the ongoing leaky run began with the 3-3 draw at Newcastle United, Liverpool had four clean sheets in five games including successive successful shut-outs at home to Real Madrid and Manchester City.

There are several reasons for the change. Disruption in the backline has been a contributory factor, with key centre-back Ibrahima Konate absent for much of that time. Enforced rotation and suspension has seen full-backs Trent Alexander-Arnold and Andy Robertson missing on occasion, while there has been a change in goalkeeper with Alisson Becker back available while Joe Gomez picked up a hamstring injury a fortnight ago. The relentless churn of fixtures has had an inevitable impact.

But as Slot has long maintained, defending isn't just about the performance of the backline. And the increased rotation in the defensive midfield area and perhaps the need for Ryan Gravenberch to be given a rest has maybe greater exposed the centre-backs in particular.

And while there has been no issue regards potency in attack - before the rare blank at Tottenham, Liverpool had netted 24 goals in eight games - that minds have occasionally been focused on going forward has at times been to the detriment of security at the back.

Of course, with Liverpool six points clear at the Premier League summit, concerns must be put into perspective. But with a decisive second half of the season having now started, Slot will be keen to not allow any shortcomings to mushroom into anything more serious.

Alexander-Arnold's performances have come under increasing scrutiny of late, although he was impressive during a cameo from the bench against Tottenham on Wednesday.

And while statistics show opponents are more likely to attack the Liverpool right - 36% of chances have come from that flank compared to 26% on the left - the last four goals they have conceded in the Premier League have been from that flank - Slot has dismissed it as an area of concern but admits there has been a pattern to the goals his team have been coughing up.

"It could also mean that we attack a lot on our right side, that they pick up the ball and then play their counter-attack over that side," he said. "I don't see anything in this. What we do have to see is how we conceded our chances, how we concede our goals and that is not only about our right side because if they attack on our right side, they still have to go to the middle to find the goal.

"If they go to the middle, it is the players who play in the middle and the players from the left side have to come inside and defend that as well.

"I do see a certain pattern in the goals we concede, but I don't see if it's the pattern if it's about Trent if that's what you mean. Not at all. Trent has had one difficult game for us and maybe a few that were okay to good.

"Mainly he had great games when he played for us this season. I know there is a lot of focus on him at the moment, but I would also like to highlight the focus on how well he did when he came in for the last half hour (at Tottenham) and how our fans reacted on him. That is what pleased me even more during that game."