Since Kenny Dalglish departed as Liverpool manager for the second time in 2012, Liverpool have almost exclusively employed a 4-3-3 formation, moving away from the 4-4-2 that Dalglish tried to install with the forward duo of Luis Suárez and Andy Carroll.
The one great exception was during Liverpool's last, and best, Premier League title challenge in the 2013/14 season, as Brendan Rodgers combined Suárez with Daniel Sturridge to devastating effect.
Perhaps Jürgen Klopp is taking inspiration from 2013/14, as signs of a 4-4-2 formation begin to emerge this season for his Liverpool team (the German has even utilised a back three when needed, such as in Liverpool’s latest victory against Brighton).
Now two years into Klopp's stewardship, Liverpool have at times started to line up differently to their traditional midfield and forward trios, supported by full-backs acting as wingers. Instead, the back four remains flat, and an energetic midfield duo allows for an attacking front four.
Klopp has deployed these new tactics in certain away games, such as in the 4-1 win against West Ham United, following the thrashing at Wembley by Tottenham Hotspur, as a model for improving both the defence and the protection it receives.
At Anfield, Liverpool still stick with their more expansive 4-3-3, but in the main (the collapse against Sevilla aside), Klopp's rotation of both players and systems has worked brilliantly in recent weeks.
New shape
Klopp's version of 4-4-2 is wholly different to Rodgers', with neither set-up a traditional 4-4-2. Rodgers employed a diamond formation to suit the strengths of Suárez and Sturridge, alongside the lack of width in the squad, with the likes of Steven Gerrard, Jordan Henderson and Philippe Coutinho all preferring central midfield roles.
By contrast, Klopp's new system is more 4-2-4 than 4-4-2, but Roberto Firmino no longer appears isolated for even an instant when the Reds are away from home, with another striker and two wingers alongside him. Meanwhile, Mohamed Salah has been a revelation both as a winger and a forward, with this formation freeing the Egyptian to play across four positions in attack.
With the front four having the license to roam and terrorise defences, there is less pressure on the midfield and full-backs to join in the attack. Therefore, they can focus increasingly on protecting the central defence and improving Liverpool's biggest weakness without a change in personnel.
Despite being reduced from three to two, Liverpool's midfield has less stress and pressure to deal with, from their stable positioning in Klopp's new set-up, and allows whichever midfield duo selected to utilise their greatest strength - their energy.
Henderson, James Milner, Georginio Wijnaldum, Adam Lallana, Alex Oxlade-Chamberlain and, to a lesser extent, Emre Can all prefer energy to tactical discipline, so when the formation takes care of the latter, they can focus on the former, knitting defence and attack in a secure and unchaotic manner.
Is this new shape the future for Liverpool?
Individual mistakes will still occur, and a number of players still have to be upgraded, either in January or the summer, but the recent signs are certainly more promising for Liverpool than during September.
Liverpool's 3-0 victory away to Stoke City this week further underlined their good form - and with no Coutinho in sight.
Klopp understandably has been rotating the side as the games have piled up week after week, weekend and midweek.
Nevertheless, it is difficult to picture where Coutinho fits into Klopp's embryonic 4-2-4/4-4-2 formation, as the Brazilian international lacks the pace of Sadio Mané and Salah to play as a winger, and can only realistically perform as a central midfielder when in a midfield three, as he does not possess the physical attributes of Liverpool's other central midfielders.
So if Klopp continues to ease this formation into Liverpool's season, and Coutinho stays at Liverpool, will he only play at Anfield? Or is the new formation a sign of things to come? Everyone knows of the summer saga with Spanish giants Barcelona over the future of the 25-year-old Coutinho, with the player himself clear in his intentions of moving to Nou Camp at some point in the future.
Whilst Liverpool admirably refused all others during the summer window, an even bigger offer (such as a £100m+ offer that is actually all up front for a change, Barca) could be the final straw, if Liverpool can use the money wisely (which is a big if).
Coutinho's sale could not only result in a replacement for the midfielder, but also defensive reinforcements which remain sorely needed.
Southampton's Virgil van Dijk still appears to be Klopp's primary defensive target - given the intense pursuit over the summer and the fiasco with Southampton, Liverpool will want to eventually end up with their man, with Barcelona seeking the same for Coutinho.
Yet this new formation would mean a direct replacement for Coutinho would not be needed. Instead, a proper No.9 could be recruited to partner Firmino in a front two. Then, as the crafty Brazilian links play with all around him, the new striker can mop up the mountain of chances that Liverpool regularly create.
In addition, there will be periods, as in September, where the Reds are struggling for form and misfiring in front of goal. Consequently, having a truly dependable goalscorer, like the rest of the Premier League's 'Big Six', could help improve those poorer periods and make all the difference in Liverpool's season.
Borussia Dortmund's Pierre-Emerick Aubameyang has once again been linked with both the Reds and Chelsea, as the German club have struggled in the Champions League this season, and will likely drop into the Europa League.
(Liverpool could almost build an entire Africa XI with Mané, Salah, Aubameyang, Joël Matip and Naby Keïta, who is arriving next summer.)
Can has been heavily linked with a move away as his contract runs out at the end of the season, with Schalke's Leon Goretzka a candidate to replace him (also on a free). With their supreme box-to-box capabilities and talent when on the ball, Goretzka and Keïta are perfect candidates for the midfield duo in Klopp's 4-4-2 - they would be good enough to make two men feel like three again.
Klopp's new formation may benefit the majority of Liverpool's playing staff currently at the club, but future transfers could also be in the German's mind as he plots another route towards success with the Reds.