Liverpool's 4-3-3 formation has been a staple of Jurgen Klopp's tenure as Anfield boss but he may well find himself with a reason to discard it, at least temporarily, after the recent displays he has seen.
The 4-0 win over Red Star Belgrade and Saturday's 4-1 triumph over Cardiff came from Klopp shifting to a 4-2-3-1 formation.
He joked after the Red Star victory that it was partly because Fabinho was playing on his birthday and it was his favourite setup. But, like a lot of things Klopp has done at Liverpool, underneath the smiley, jovial exterior there has been a carefully considered decision.
'It looked good, it made sense to do it,' Klopp said in his press conference ahead of Cardiff. 'It was the right thing to do with these players in these positions. For sure, it is not the last time we use it in this way.'
Firstly, Klopp's hand may have been forced somewhat with injuries to Jordan Henderson and Naby Keita. James Milner overcame a hamstring problem remarkably quickly but Klopp is right to be cautious in returning him to the starting line-up.
With Fabinho and Georginio Wijnaldum his only fully fit midfielders and Adam Lallana and Xherdan Shaqiri more comfortable operating in an attacking midfield position, Klopp shuffled his pack.
Mohamed Salah plays as the lone striker in a 4-2-3-1 but can interchange with Roberto Firmino and Sadio Mane. But both Salah and Firmino have dropped remarkably deep during patterns of play in Liverpool's last two games and both have scored after making late runs into the area.
Take Firmino's goal against Red Star, Liverpool's first of the night. They bustle Red Star out of possession and Firmino cushions the ball into Shaqiri, who slots through onrushing left-back Andrew Robertson while Mane, Salah and, wide on the right, Trent Alexander-Arnold race forward.
Firmino, however, spins into space 10 yards to his left before starting his run as Robertson approaches the byline.
The pull-back reaches him as he arrives in the penalty box and, with an extra moment of time in the area, controls and slots home to give Liverpool the lead.
It was similar for Liverpool's first on Saturday against Cardiff. The move starts with Salah closer to the halfway line, back-heeling the ball into Alexander-Arnold.
Once he delivers into the area, Salah charges diagonally into the space created by the cross and his gamble is rewarded when the ball breaks into his path. 1-0 Liverpool.
Firmino drops deep again for Liverpool's second against Cardiff. He joins Fabinho and Wijnaldum in midfield and entices Bruno Manga out of position before turning and running into the space that has opened up.
Cardiff scrambled and momentarily recovered before Mane eventually lashed in a formidable strike.
The full-backs play a key-role in this setup. Alexander Arnold and Robertson, or Moreno on Saturday, push so far forward it allows Mane, Salah and Firmino to group closer together.
One drops deep not only to support a two-man midfield but to pull a defender away and create space for the other two while confusion grows in the back line of the opposition.
The roles of Wijnaldum and Fabinho are crucial in providing a foil for the defence.
When the full-backs push forward one, normally Fabinho, can drop in almost deep enough to be a third centre-back.
When Liverpool lose possession Firmino, Mane and one of Shaqiri or Lallana are quick to press but Salah has, at times, held back.
When Liverpool win the ball, it is played ahead of him rather than slotted into his feet as his pace will nearly always take him clear of a defender.
Next for Liverpool is an Arsenal side unbeaten in 11 at the Emirates Stadium on Saturday.
Klopp has a big decision to make over his formation, with his 4-3-3 setup much more tried and trusted against established sides.
The 4-2-3-1 formation, however, will have more of the unknown t for opponents and also allows him to have a fourth attacker in either Lallana or Shaqiri - the latter has looked particularly impressive of late - to dovetail with Mane, Salah and Firmino.
The early signs suggest the regular front three are relishing the latest tactical alteration and look capable of flourishing further alongside Shaqiri.
That could be considered too risky to start with away to Arsenal. But if Klopp goes for it, it could also lay the foundations to a gripping game.