Roberto Firmino became Liverpool's second most expensive signing when Brendan Rodgers brought him across the channel from Hoffenheim in 2015 for an initial fee of £29m - the Reds' record signing at the time? Andy Carroll for £35m.

While one has wound up perennially on the West Ham treatment table the other has become a part of one of the most feared front threes in the world, helping his side to become Champions League finalists and the Premier League's best chance at dethroning Manchester City.

'Bobby', as he has been affectionately nicknamed by the Kop, scored 15 goals and assisted a further seven in as he appeared in all but one of the Anfield outfit's league games last season and recorded an astonishing 10 goals and eight assists in just 13 Champions League games.

However, something isn't quite right with the Brazilian this season - he has just four direct goal contributions all season in the league and his average match rating of 6.94 in all competitions so far is dwarfed by his previous 7.69 (WhoScored).

So what's going wrong this season for the 27-cap international? While Klopp's surprise reluctance to stick with the 4-3-3 setup which resulted in such success last season has seen his side become one of the defensive powerhouses of the league, the new 4-2-3-1 is not getting the best out of his number 9. The German has maintained that tactical variety gives his side their best chance of winning the title, but Firmino looks to be suffering from an ever-changing system.

The introduction and good form of Xherdan Shaqiri have meant that the Swiss is difficult to leave out - the new formation accommodates all three of Liverpool's wingers - but his presence limits the effect of Firmino greatly.

The right-footer is up there with the best false-nines in the world, as his effectiveness in dropping back from his forward role to feed the Reds' rapid wingers is what made his side tick last season.

The 27-year-old, despite the record-breaking exploits of Mo Salah, has been identified by many as the key component in Jurgen Klopp's front three as his movement allows the Egyptian and Sadio Mane to make inverted runs on goal; John Barnes went as far as to say that we would never have seen the Salah of last season if not for Firmino.

Klopp seems to have figured out that the £72m man cannot lead the line in this system, as the pockets into which he would usually drop would be occupied by the third attacking midfielder, so the former Tombense man has slotted into a number 10 role.

The dangerous Salah is now the main man up front when Klopp uses this approach, and even he appears to be predictable at times.

A solution would be for Klopp to revert to a classic 4-4-2, in which Firmino can start up front with Salah, this gives the former the option of dropping deep as opposed to being forced into that position from the get-go where he is quickly found out.

The four-man midfield behind the two strikers offers the defensive security which Klopp craves as they can press opposition off the park with all areas of the pitch covered so it seems like a win/win - if Firmino can rediscover his form.

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