Manchester City's final Champions League group stage game at RB Leipzig should have been a breeze for Pep Guardiola regardless of what happened on the pitch.
His side secured top spot in Group A after beating Paris Saint-Germain on matchday five, avenging their defeat at Parc des Princes and confirming to Europe that they will be serious contenders for the European Cup again.
Guardiola - who has often been critical of fixture congestion, injury/fitness problems and the use of only three subs in English football this season - had the chance to rest his big stars and perhaps lean on some of the talented youngsters coming through the academy he likes to talk about.
And in fairness, the Catalan coach did make seven changes, though that didn't stop City's starting lineup looking like one capable of storming to a Premier League title. A handful of academy products also made the bench, including Cole Palmer who has impressed already this season.
And yet, with nothing on the line, a 2-1 loss in an empty stadium in which Guardiola's side made chances yet looked understandably ropey from the rotation, they still found a way to sour the overall mood - isn't that just typical of City?
Kyle Walker put in one of the single worst performances in the Sheikh Mansour era (let's not rewrite history and say City have been at this level forever). He lost the dangerous Dominik Szoboszlai for Leizpig's opening goal, and late on with the visitors getting a foothold again, decided to try to obliterate the ankles of Andre Silva for seemingly no reason.
The challenge was so gratuitous that it may even be enough for UEFA to look at and add to Walker's automatic one-match suspension, which would throw an even bigger spanner in City's knockout stage works.
Tempers flared toward the end of the game in Saxony, but Walker - one of City's most senior players - let the team down and has brought a level of attention that Guardiola surely would not have wanted.
A quiet night in Leipzig will see the coach asked about the conduct of one of his most trusted players, how will that affect the team, how it may be a reflection on a team known for their tactical fouling as a whole.
Walker's done well to repair a reputation as a luxury liability in recent years, elevating himself to the top of the game and being well worth the £50m that City paid Spurs for him. And yet one awful and foolish display is enough to bring those doubts back to the surface. He has to own that for himself and his teammates.