Virgil van Dijk's return to form has only reaffirmed the challenge Liverpool will have in the future.
The centre-back transformed Jurgen Klopp's side after arriving for a club-record £75 million in January 2018. He's been the bedrock of the team that won six major trophies, including the Champions League and Premier League, along with two runners-up medals in the respective competitions.
And having been handed the captaincy after Jordan Henderson's summer departure, the Dutchman has looked like his commanding self this term after he endured a dip in 2022-23.
After proving his detractors wrong, it appears that the 32-year-old still has several years at the top. Out of contract in 2025 at Anfield, it remains intriguing what will happen in the long term. If van Dijk does indeed pen fresh terms on Merseyside, there's a significant chance that will be his final Merseyside deal. Then the task for Klopp and his recruitment staff will be to begin the search for a replacement. It will be a tall order.
In fairness, Liverpool have options currently at the club. Aged 24, Ibrahima Konate is still several years short of his peak. He's already van Dijk's established defensive partner when fit.
Joe Gomez, meanwhile, is entering what are deemed the best years of his career at 26. And if Jarell Quansah continues his eye-catching progress amid a breakthrough season, he could well become a regular. The academy product has played nine games in total, including a full Premier League debut. There will be hopes that the 20-year-old can nurture himself into a regular down the line.
But Liverpool cannot forget another fledgling talent quietly looking to thrust himself into the frame. For the past three years, Sepp van den Berg has been out on loan garnering regular first-team experience. One-and-a-half seasons were spent at Championship side Preston North End where he recorded a total of 50 appearances.
Last campaign, he stepped up to the top flight when joining Bundesliga outfit Schalke. However, a serious ankle injury suffered early on during his spell at Die Konigsblauen restricted van den Berg to just 10 outings. Four of those were starts after he regained fitness towards the end of the campaign, though, proving he was over his setback.
After what proved to be a challenging 2022-23 that saw progress stagnate, Liverpool opted to send van den Berg back to Germany in the summer and join Jurgen Klopp's former side Mainz. Despite the Rhineland-Palatinate club struggling so far as they sit in the relegation zone, the Holland under-21 has flourished.
Van den Berg has established himself in the starting line-up at the Mewa Arena, with all but two of his 11 appearances so far from the outset. The highlight has been a 2-0 victory over RB Leipzig, with the 21-year-old Mainz's second-best performer with a match rating of 7.76 per WhoScored. That display earned him a place in the Bundesliga Team of the Week as he rubbed shoulders with Harry Kane.
What's more, van den Berg's stats in 2023-24 augur extremely well. Granted, the lowly position of Mainz means there's been defending aplenty to keep van den Berg occupied but that's a situation that Liverpool won't mind at all.
According to the Bundesliga website, he has won the second-most aerial duels (60) and third-most tackles (129) in the division so far - ahead of Bayern Munich's pair Matthijs de Ligt, and Kim Min-jae who cost a combined fee reported to be £111 million. Meanwhile, FB Ref have van den Berg winning 50 aerial battles, which places him 11th in Europe's top five divisions - and just one place adrift of van Dijk.
Van den Berg isn't short of pace, either. Last term, he clocked a top speed of 33.06km/h, which was higher than Kop legend Sadio Mane. This season, that has increased to 34.78km/h.
To date, van den Berg has made four appearances for Liverpool. Interestingly, Klopp got the chance to run the rule over him after attending a Mainz friendly in September at their former Bruchwegstadion home.
In truth, this is likely to be van den Berg's final season on loan. He'll want to find a permanent home somewhere, whether that be Anfield or elsewhere. Should he continue in the manner he's exhibited in the opening third of this campaign, it'll give Klopp and his backroom team something to ponder.