Sami Hyypia remains Liverpool’s greatest signing, pound for pound, in the modern era, but Philippe Coutinho may yet surpass the Finn if the 24-year-old can continue his new run of form over the long-term.

Costing just over £8 million himself, Coutinho’s signing from Inter Milan is already one of Liverpool’s best purchases in this century, and probably Brendan Rodgers’ best signing for the club.

Daniel Sturridge may dispute that claim, while Nathaniel Clyne and James Milner are ironically building their cases under Rodgers’ successor, Jürgen Klopp. However, with every season that goes by, Coutinho has grown in stature and significance for Liverpool since he arrived in January 2013.

Exciting many in Brazil during his youth, Coutinho struggled when making the move to Europe, joining Italian giants Inter Milan. Former Liverpool manager Rafael Benitez was impressed with the Brazilian international, but he really started to make his mark on loan at Espanyol, managed at the time by current Tottenham boss Mauricio Pochettino.

Having failed in re-signing Tom Ince from Blackpool, the Reds turned to Coutinho, who again was finding his football limited in Milan.

He immediately made an impression at Anfield with some spectacular passes and assists, influencing Sturridge’s hat-trick away to Fulham and orchestrating Liverpool’s 6-0 win at Newcastle United.

Already Coutinho was being compared to David Silva for his ability to cut through defences with such precise, imaginative passing. But in the following season, he arguably played a more reserved role as the likes of Luis Suarez, Sturridge and Raheem Sterling wreaked havoc.

Coutinho played in a deeper midfield role alongside Jordan Henderson, with Steven Gerrard behind and Sterling ahead in a 4-4-2 diamond formation. However, the Brazilian still enjoyed a considerable impact on Liverpool’s title challenge, with long-range strikes against Fulham and Manchester City allowing Rodgers’ side to maintain their momentum in 2014, before it was sadly cut short by Chelsea and Crystal Palace.

Coutinho has improved year on year at Anfield

Nevertheless, Coutinho’s importance to the side was expanding, as not only could the young talent operate further forward, but he showed in that 2013/14 season his tenacity and relentlessness in midfield, regularly winning the ball back and adding to Rodgers’ direct style of play.

It would serve as useful preparation for the future under a certain German manager, but before Klopp’s arrival Coutinho maintained his starting role for the club, once again playing further forward with the departure of Suarez.

Yet despite featuring in the 2015 PFA Team of the Year, the Brazilian was beginning to come under fire for his lack of consistency and tendency to disappear from games, now only influencing matches through the occasional long-distance goal rather than those defence-splitting passes that he showcased when he arrived at Anfield.

This theme continued into last season, with Rodgers being replaced by Klopp, while Sterling also left for Manchester City, so consequently Coutinho’s stock at Liverpool was raised even higher, even if his form had not quite followed such rapid progression.

Undoubtedly he remained a brilliant, and vital footballer for Liverpool, becoming acquitted with Klopp’s physically demanding and sharp style of play, while forming an effective trio with Roberto Firmino and Adam Lallana.

However, after a pre-season under the new manager, Coutinho is beginning to enter his peak, and that long-awaited consistency that Liverpool fans hoped he possessed is now emerging.

Not only is Coutinho now influencing the outcome of matches on a regular basis, but he is harnessing both his decisive passing and spectacular shooting together to devastating effect.

In a quartet possessing such speed of mind and legs in Firmino, Lallana and Sadio Mane, Coutinho is the figure who adds that extra stardust into Liverpool’s performances, making them irresistible going forward. Firmino provides the trickery, Lallana the energy, Mane the directness and Coutinho brings it all together, and Liverpool have not looked back under Klopp this season.

Top of the league, with thirty goals in eleven games, means Liverpool, three years on, have another great chance of challenging for the title – only this time, Coutinho is the spearhead rather than part of the supporting act.

Coutinho still has unfinished business at Liverpool

Such form has not gone unnoticed, with Coutinho’s name circulating among the gossip columns in recent weeks, heavily linked with Barcelona, while there have been questions over Real Madrid as well.

Rumours over Coutinho's future began after Liverpool’s near miss in the Premier League in 2014, but he was far too raw and erratic for the Spanish giants at that stage, hence Barcelona’s interest in Suarez, Coutinho’s former club-mate, who was much closer to the finished article.

That signing has paid dividends for Luis Enrique, with Suarez now arguably the best out-and-out striker in the world, and attention has turned back to Coutinho, now that he is seemingly following a similar path to the Uruguayan with his rising progress at Anfield.

Indeed, Suarez went up a level once Rodgers arrived at Liverpool, and has taken that further in Spain, and Klopp has elevated Coutinho, alongside many other Liverpool players, since his arrival over a year ago.

However, even if Barcelona now feel Coutinho is ready to make the move to Cataluña, the Brazilian has plenty of unfinished business in England, and has always shown admirable loyalty to the club he believes revitalized his career.

Moreover, before Coutinho can play alongside Neymar at club and international level, Suarez and Lionel Messi need to show signs of decline, to emphasize that Barcelona cannot rely on their superstar trio for much longer.

Messi and Suarez are both 29, therefore that scenario may be arriving in the next couple of years. However, for the moment, there is no place for Coutinho in the Barcelona side, unless he wants to compete in a deeper position with the likes of Andres Iniesta and Ivan Rakitic.

Coutinho is happy under Klopp and needs to maintain this level of performance if Liverpool are to remain at the top of the Premier League, with his quality now regularly matching his status as the cornerstone of this side going forward.

At present, Coutinho is world-class – more of this and he will become an outright world-class player, and then he will have to decide if his future ambitions lie away from Liverpool.