As Lee Carsley prepares for his final game as England's interim head coach against Ireland on Sunday, what legacy will he leave for Thomas Tuchel?
Carsley appeared on the surface to be the continuity candidate when he stepped up from the Under-21s to replace Gareth Southgate in August, presenting himself to the country as "a safe pair of hands".
His record of coaching innovative football, however, suggested he was always likely to deviate from Southgate's conservative approach, and he has proved an experimental and populist England boss, prepared to roll the dice and make brave calls.
His side have played exciting attacking football at times but displayed a fragility, particularly at the back, which was rarely present under Southgate and reflects their inexperience.
Carlsey occasionally looked out of his depth, particularly when questioned on his own role and future, but barring an unexpected hiccup against Ireland at Wembley, he will have fulfilled his remit of returning England to the top-tier of the Nations League - ensuring Tuchel avoids the headache of an unwanted play-off in March.
Carsley has helped to usher in a new generation, handing debuts to six players in Angel Gomes, Morgan Gibbs-White, Noni Madueke, Curtis Jones, Lewis Hall and Morgan Rogers; restoring Dominic Solanke to the squad after a seven-year absence; and turning Rico Lewis and Anthony Gordon into regulars after their bit-part roles under Southgate.
All of the above worked with Carsley at U-21 level, demonstrating the benefit of having a coach who knows the England pathway intimately.
Jones marked his England debut against Greece on Thursday with a brilliant goal and both he and Gomes look strong contenders to challenge Kobbie Mainoo for a place in midfield next to Declan Rice. If all three continue to progress, the position may not be such a concern under Tuchel as it was for Southgate.
Madueke has immediately looked at home and offers the German another direct wide player in the front three, while Lewis' versatility and technical quality make him a hugely valuable player at this level. Hall has a chance to become a regular given England's lack of depth at left-back.
Carsley's most significant contributions to Tuchel's tenure, though, will surely come as a result of his brave experiments in the home and away fixtures against Greece, which had such contrasting outcomes.
In England's 2-1 defeat at Wembley last month, which still seems likely to be the defining memory of Carsley's interregnum, the former Everton midfielder threw Southgate's caution to the wind with an ultra-attacking set up, including five forwards but no recognised striker.
Carsley gave many supporters what they wanted by shoehorning Gordon, Bukayo Saka, Jude Bellingham, Phil Foden and Cole Palmer into his XI, with Palmer as a deep-lying playmaker and Bellingham a false nine.
The result was a shambolic England display, lacking coherence and structure, and a deserved win for Greece, which looked in danger of scuppering Tuchel's start until this week's successful revenge mission in Athens.
The match may have damaged Carsley's reputation, giving the impression of an unserious coach prone to bowing to public pressure, but it painted Southgate in a better light and was arguably the biggest favour the interim could have done for Tuchel.
Southgate was criticised for failing to find a place for all of England's gifted No10s but there will be far less pressure on Tuchel to accommodate Bellingham, Palmer and Foden, not to mention two wingers, after Carsley's failed experiment.
It was an inadvertent gift to Tuchel, helping to reinforce the notion that a coherent system is more important than big-name personnel - a principle that will surely be beneficial to the former Chelsea head coach in building a team capable of fulfilling his remit of winning the 2026 World Cup.
This principle was also underlined by the reverse fixture on Thursday, when Carsley opted to leave out Harry Kane, England's biggest-name star, in favour of Ollie Watkins, who he plainly felt was better-suited to England's game-plan of pressing high and stretching the Greek defence.
It was an enormously bold call in the circumstances - the visitors needed to win by two goals to take control of their Nations League group - and offered the country a glimpse of a future without England's record goalscorer - which may prove consequential for Tuchel.
Now that Carsley has ripped off the Kane-shaped plaster by leaving him out of a must-win game, it should be less controversial for the German to overlook the captain if he decides England need a more mobile forward like Watkins or Solanke for certain occasions.
There is still time for Kane to change the narrative against Ireland, with the 31-year-old to be restored to the line-up, and there remains a possibility that England will slip up, which would leave Carsley's legacy in tatters and Tuchel likely facing a disrupted first camp in March.
As it stands, however, the interim head coach has smoothed the way for his successor to tackle the two issues which most undermined Southgate's tenure towards the end: how to accommodate England's multiple world-class No10s and how to decrease the team's reliance on Kane.