This transfer window is fast turning into one Liverpool fans are beginning to dread.

At the start of last month, the forums were rife with the Anfield faithful excitedly checking the news and scouring transfer rumours for the latest big names set to join the club on their return to the Champions League.

Names like Virgil van Dijk, Naby Keita and Mohamed Salah were being bandied around as though they were already done deals as Jurgen Klopp looked to get his new players on board as quick as possible.

Fast forward a few weeks and the latter is the only one to have signed, with the Reds withdrawing their interest in Van Dijk after accusations of tapping up while Red Bull Leipzig continue to play hardball over their dynamic midfielder.

Even obtaining those targets will be of little consolation to Liverpool fans should reports come to fruition that Philippe Coutinho will join Barcelona.

The Brazilian has been rumoured to have been of interest to the Catalan giants and sure enough they have confirmed that interest with bid of £72m, as per Sky Sports.

Klopp has insisted the midfield wizard is not up for sale, but unfortunately for the Reds it is beginning to echo a similar situation a few years ago when Luis Suarez made the same move from Merseyside to Spain.

While Coutinho hasn't quite hit the incredible standards the Uruguayan hit in his final season at Anfield (something very few players would claim they have), he has undoubtedly been key over the last few seasons, with many claiming he is the best player in Klopp's side.

That's the reason that Barcelona are so keen to bring him in and revitalise their midfield after finishing second to Real Madrid in La Liga last season.

Since signing for the bargain fee of £8.5m, Coutinho has managed to improve every season, culminating in his best campaign last year with 13 goals and seven assists.

It's not just his attacking output that shows his importance to the side, though; the Brazilian's dribbling ability and vision is just as important (he managed 58 key passes and averaged 2.3 dribbles per game), while the fact he has adapted so well to Klopp's system is testament to his work-rate and understanding of a pressing system.

While there is quality in Liverpool's ranks; Sadio Mane, Roberto Firmino and Salah should form a deadly attack while Adam Lallana adds some creativity and guile, there arguably isn't a player that brings what Coutinho does to the Liverpool side.

And while Van Dijk and Keita would help make a stubborn defence and energetic midfield, they aren't one of a kind players in the same way. At the very least, the business Liverpool should be most concerned with is persuading their midfield maestro to stay for at least another year in a similar way to Suarez did amidst Arsenal's interest.

If Coutinho moved on, even bringing those two in would represent a huge step backwards for a club just getting back to the top.

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