In time, it will become a mere footnote as bigger challenges and grander occasions come thick and fast, but the first steps of the second Brendan Rodgers era will begin in Yokohama today.

Two secretive closed-door bounce games in Portugal notwithstanding, a friendly against Yokohama F. Marinos serves as the first look at how Celtic will set up under their returning manager. Early days, of course, but fans will tune in with excitement for clues as to what Rodgers has up his sleeve for the coming season.

But what should we be expecting from him? Well, his fundamentals are unwavering: “The three basic rules are: be intense and aggressive, be creative and also have one more player in midfield than our opponents. That's my three basic rules and has served me well in my career, but my teams are flexible and can play different systems when required.”

Rodgers has indeed shown extensive flexibility throughout his career. He will also inherit an embarrassment of riches from Ange Postecoglou, albeit a squad that was very much built in the former manager’s image, to play his specific brand of football. But that makes it all the more fascinating for supporters eager to see where this group can go next. Here, Herald Sport looks at how Rodgers’ Celtic 2.0 could take shape, based on his career to date.

Full-backs

The most eye-catching change Postecoglou introduced in the early weeks of his tenure was the use of inverted full-backs. This was a departure from previous setups and a tactical approach largely unseen in Scottish football.

Full-backs were a key tenet of Rodgers’ Celtic but not quite in the same way. The marauding Kieran Tierney was given license to join in attacks high and wide, which often saw the more conservative Mikael Lustig tuck in and cover on the opposite side of the pitch to form a back three. The switch to an inverted full-back style was of particular benefit to the previously unfancied Greg Taylor.

The Scotland international's game had never been about bursting through on the overlap outside a left winge, but this tweak maximised many of his key strengths. Taylor is technically good, extremely fit, and has the tactical intelligence to pick up spaces where he can be most effective. It was not uncommon to see him appear in the final third and receive passes on the half-turn before looking to set up a team-mate.

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How he fits into a potentially altered Rodgers side will be intriguing to watch. On the opposite flank, Alistair Johnston has the physical attributes to excel in a more traditional full-back setup. Strong, fast, and full of running, the Canadian is very much the right-back Rodgers may have wished he had in the latter stages of his first Celtic spell, when it became Lustig was no longer at his peak and Jeremy Toljan proved an unsuccessful loan option.

Midfield

Rodgers has preferred to sit two players at the base of his midfield when starting attacks. This can offer more passing options and greater solidity if Celtic lose possession in their defensive third.

Two deep-lying midfielders is not what Postecoglou implemented per-se, but the impact of the inverted full-backs was his way of ensuring those extra numbers in the build-up, and allowing advanced midfielders to take up more threatening positions. Rodgers has possibly provided an early clue that there's a more traditional set-up on his mind with the imminent arrival of Kwon Hyeuk-Gyu, a player stylistically compared to Manchester City’s midfielder enforcer Rodri.

Scott Brown as the anchor was a crucial cog in the first Celtic machine Rodgers constructed, but the position was redefined under Postecoglou. Callum McGregor assumed the role at the base of midfield but he was not a defensive midfielder, instead tasked with being a creative influence from deep.

If there is to be a change in midfield shape, it raises intriguing questions as to the role of others, given Postecoglou’s implementation of two more attack-minded players – generally Matt O’Riley and Reo Hatate - was so prevalent over the past two years. O’Riley and Hatate are dynamic, intelligent footballers who could easily slot into a midfield two but with more license to break forward – as McGregor and Olivier Ntcham often did when paired with Brown.

Celtic often operated with a number 10 in Tom Rogic under Rodgers, a role which has become less common at the top level with the increased attacking emphasis on full-backs and exploiting wide areas. At Leicester, Rodgers regularly operated with James Maddison as a 10 in a formation similar to that of his Celtic team, but this was not his only approach. For example, he was also willing to shape up in a 3-4-2-1, with the likes of Maddison and Ayoze Perez deployed in a more hybrid, narrow winger/attacking midfielder role with the width coming from two wing-backs pushing high.

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The fascination with this first public outing since returning to Celtic is you could make a case for implementing any of these systems given the players available. Celtic have such an abundance of midfield options it is even possible to make a case for the 3-4-3 which almost propelled Liverpool to the Premier League title in 2013/14. This involved a midfield diamond with Steven Gerrard at the base, supported by Jordan Henderson and Philippe Coutinho with Raheem Sterling playing off Luis Suarez and Daniel Sturridge.

It would be a surprise to see Rodgers go back to this system, but the point is there is such an array of possibilities to choose from that anything could happen, an exciting prospect for Celtic fans.

Strikers

Kyogo signing a new deal reaffirms his status as Celtic’s first-choice striker, possibly the most important piece of business Rodgers will conduct this summer. The Japan international is a different profile to Rodgers’ go-to forward of his first Celtic stint in Moussa Dembele. Kyogo was barely involved in the build-up under Postecoglou, and it was not unusual for him to only touch the ball a handful of times – one of which, to be fair, was often a goal.

Dembele enjoyed dropping deep at times under Rodgers with the likes of Scott Sinclair moving in off the flanks to stretch opposition defences in behind. But with Kyogo at his most effective when making those bamboozling runs, there will likely be more similarities with Rodgers’ use of Jamie Vardy at Leicester. Despite his advancing years, Vardy was highly productive under Rodgers’ management, scoring 23 times in their first season working together, an example of the manager’s ability to tweak and tailor systems to get the best out of certain players.

The Rodgers effect - who's next?

As with Vardy, Rodgers has shown a real flair for adjusting his approach to maximise output from players, or to transform their role entirely. His use of Gerrard – best-known as being a goalscoring box-to-box midfielder – in front of the back four at Liverpool was widely lauded. Gerrard’s dynamism had naturally declined as he aged, but the switch ensured the team still got the best from his wide range of passing, and he struck up a particularly close understanding with Suarez.

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At Celtic, Sinclair’s career was revitalised by Rodgers. He is the only manager to have turned the winger into a genuine goal threat. He was among the manager’s first signings at Swansea City in 2010, scoring 28 goals in 50 appearances that season.

His goalscoring output was nothing like that again until he moved to Celtic, where he scored 62 games over four campaigns. Others, such as Dembele, Tierney, Stuart Armstrong and James Forrest, all took their careers to another level under Rodgers, and it stands to reason he could have that same galvanising effect on a current squad brimming with potential.