London - Fortress Anfield has become even more impenetrable for visiting sides in the 13 months since Liverpool made Virgil van Dijk the world's most expensive defender, but the commanding Dutchman's absence for Bayern Munich's visit in the Champions League leaves Jurgen Klopp with a selection headache.
Van Dijk is banned for the last 16, first leg on Tuesday after being booked three times as last season's finalists squeezed through the group stage by the narrowest of margins thanks to more goals scored than Napoli.
In stark contrast to their form in the Premier League, where Liverpool have been beaten just once all season, Klopp's men lost all three of their group games on the road against Napoli, Paris Saint-Germain and Red Star Belgrade to underline the importance of taking a lead to Germany for the second leg on March 13.
Three wins at Anfield pulled them through to the last 16 and Van Dijk has yet to taste defeat in 25 Premier League and Champions League games on home soil as a Liverpool player, keeping 16 clean sheets in the process to tighten up a leaky defence that undermined Klopp's first two years in charge.
"Of course he’s a massive miss, a big miss," said Liverpool captain Jordan Henderson.
"I think he’s played every game this season so I think you can see how important he is for us as a team."
Missing the £75 million man is a big enough blow, but Liverpool will also be without centre-backs Joe Gomez and most likely Dejan Lovren through injury.
Midfielder Fabinho is therefore likely to deputise at the heart of the defence alongside Joel Matip.
"In the Champions League against Bayern Munich it's not an easy job," said Klopp at the prospect of Fabinho playing out of position.
"But we thought it makes sense we don't leave our last row alone defending against Bayern, so it all depends how we defend in general."
Another of Klopp's former pupils, Robert Lewandowski, poses the biggest threat for Bayern.
The prolific Pole won two Bundesliga titles under Klopp when the pair were together at Borussia Dortmund and also lost the Champions League final against Bayern in 2013 before Lewandowski was lured to Bavaria a year later.
"He (Klopp) made a huge impact on my career. I have to be thankful to him because of what we did together at Dortmund," Lewandowski told UEFA.com.
Bayern have been dominant in the Bundesliga since Klopp's Dortmund won back-to-back titles in 2011 and 2012, but are playing catch up in the title race to Lucien Favre's outfit this season.
"After being six years the dominator of the league, it was clear this year would be a more difficult year. It is a completely normal situation," said Klopp.
"To become the champion, you need to have the desire of a newcomer combined with the quality of a real contender. In the beginning of the season, after being six years champions, maybe they didn't have that but now they are chasing the leaders so they have it back.
"The situation in Munich, from my point of view, makes them even more dangerous, more of a threat than they were before."
However, while Lewandowski, the in-form Kingsley Coman and the creativity of James Rodriguez and Leon Goretzka could pose plenty of problems for Liverpool's undermanned defence, it is at the other end Bayern could also be exposed.
Ajax's youngsters exploited Bayern's weakness against pace in the group stage, while Bayer Leverkusen and Augsburg have also given Klopp extra encouragement in recent weeks in the Bundesliga.