Pep Guardiola's tactical revolution at Manchester City will walk out into its biggest test so far at the start of the coming season.
Twelve months ago the shape of City's side against Sunderland was something new, even after all the years of chopping and changing under the plethora of managers the club had eaten its way through. The fascinating movements of the two full-backs, drifting inward and forward to suddenly become central midfielders -- Bacary Sagna and Gael Clichy even overlapped at one stage, leaving the right-back in left midfield and vice versa -- was just part of Guardiola's initial "Welcome to England" tinkering.
This structural change alone dragged Sunderland's nominal forward midfielders into a congested midfield on that occasion, where they found their own confused full-backs trying to do their usual job of tracking City's flank defenders.
This in turn allowed City's wide attackers, Nolito and Raheem Sterling on that occasion, to move into largely unoccupied spaces where Sunderland's full-backs should have been. There were many more tactical innovations to come of course, among them Aleksander Kolarov striding around central defence like Franz Beckenbauer, Fernandinho playing at right-back and -- on at least one occasion -- City turning out with no attackers whatsoever.
On that bright opening day of the season, Sunderland -- to be relegated the following May -- not only held on for a while but actually earned a deserved equaliser. The home side only managed to grab the three points with an unlucky own goal right at the end of the match.
City's players were still getting used to a totally alien set-up. The pace of the game had been slow and, despite massive advantage in possession, it was evident that City's players were still unfamiliar with the runs that they needed to make.
Sergio Aguero had had a notably quiet game up front that day, but this was about to change radically in Romania, where City played local champions Steaua Bucharest in the qualifying round of the Champions League.
A decent side was quickly made to look like they were in complete shambles, as City's movement and speed of thought had been notched up a level or two from the opening game in the Premier League. The players' movement was more fluid and triangles of sharp passing between them became a mesmeric nightmare for Steaua's poorly arranged defence.
At that early stage, some critics saw City as potentially overwhelming champions. Others attempted to play down this performance on the grounds that the home side had been undeniably poor. As City eased into the season, it was apparent that there was a developing problem at left-back, where Kolarov was being asked to play inside and on the other flank and where both Sagna and Pablo Zabaleta seemed sluggish when operating in the way the new trainer wanted them to.
All four flank defenders were well over 30 years old. While experience helped them with positioning and anticipation, lack of speed and energy gradually exposed them in Guardiola's ambitious system.
What had initially looked like a swift and decisive breakthrough rapidly became a weight around City's neck. Guardiola's need for fast overlapping from his chosen full-backs just wasn't happening, and the opposition were quick to realise it.
As Chelsea and Tottenham developed into the season's main players, City were gradually left in their slipstream, their system ill-fitting the personnel the Catalan had inherited from Manuel Pellegrini.
In effect, the tactical revolution at City had been put on hold. Until now.
What Premier League crowds will see this season should be markedly different. With City's heavy recruitment drive having brought in a variety of talents in a variety of positions, all eyes will be on the full-backs. In Kyle Walker and Benjamin Mendy, Guardiola at last has the kind of players he wants filling his critical positions. Mendy's injured thigh muscle might mean he will sit out the much-anticipated opener against Brighton, but Danilo can slot in at left-back and centrally, providing cover for a variety of positions.
A year after his much-heralded arrival, the Catalan is at last in a position where he can be properly judged. On the back of his first-ever season without a trophy, he will relish the opportunity to put that right. The revolution in personnel that the City supporters have been crying out for over the last two seasons or more has at last taken place.
With the replacement of old hands with young legs, the trusty old brigade have been moved on to be replaced by the next generation. With Walker, Danilo and Mendy, as well as new goalkeeper Ederson Morais, Bernardo Silva, Sterling, Leroy Sane and Gabriel Jesus, City's average age has plummeted.
Guardiola's reputation will now stand or fall on City's ability to accommodate one of the biggest transfusions of new blood ever seen in English football. He will at least have the players he wants to manage City's assault on the game's prizes in 2017-18.