Liverpool are now within touching distance of becoming Premier League champions.

They cannot afford to be complacent, but their performances across the first 21 matches of the season have put them in an almost unassailable position. They have picked up 61 points from those matches, which is more than any team has managed in the history of the top five leagues in Europe at this point of the season. They also haven't lost in the league in over a year - right now, they truly are the best team in England and in the world, as their Club World Cup victory indicates.

The big fat Liverpool quiz of 2019 - how much do you remember about the last year at Anfield?

A huge part of their success is down to the front three of Roberto Firmino, Mohamed Salah and Sadio Mane. Last term, they scored 68 goals between them in all competitions, whilst this time out they have managed 36. Their performances last year even led to all three of them finding themselves in the top 20 of the latest Ballon d'Or rankings, with the latter two finishing fifth and fourth respectively.

Given their contribution to the team's success, you wouldn't initially think of calling the trio a problem. But in the long term, that could very well be the case. As it is now, Firmino is 28 years old, whilst the African duo are 27. They are no longer in their formative years, but they are far from bringing the curtains down on their careers. You could even argue that they are yet to hit their peak - a study from 2014 showed that the average age of a team that wins the World Cup is 27.5.

They will not be around forever, though, which means that Liverpool need to plan for the future. The issue is, which top players will move to Anfield whilst knowing that they will not receive considerable playing time for at least another two or three seasons? For example, Timo Werner, a reported target, is said to have turned down a switch to Merseyside as he feels he will not play enough.

The Reds have also been linked with stars such as Kylian Mbappe and Jadon Sancho. Their ability would undoubtedly bring something to Klopp's squad, especially given their age, but would they even find a spot in this side? It is not as if Liverpool would be in a position to play hardball to sign them - other clubs are also interested in the pair's services. The European champions will one day be ready to add them to their squad, but by then it may already be too late.

For now, the formidable trio can continue to bring success to Liverpool, but that could come at a detriment to long-term plans. Even Sancho and Mbappe could struggle to replace any of those three whilst also not disrupting the well-oiled machine the Reds have become.

At some point, Klopp will have big decisions to make as he faces a crucial question - how exactly do you create a succession plan for arguably the best front three in the world?

Meanwhile, Liverpool must sign this Premier League man after his latest stunning display.