Real Madrid's first defeat of the season, against Real Betis, brought about a controversial decision from Jose Mourinho. He chose to substitute Arda Guler during the second half and bring on Diamonde on the right wing, even though the Turkish player had been the best of the Madrid side's players on the pitch.
According to the Spanish newspaper "AS", Mourinho knows better than most that few decisions come easy when you manage Real Madrid, if any of them do at all.
The Portuguese coach admitted as much himself. One of the calls he made during the match that ended in the white side's first defeat of the season, at Real Betis's stadium, was perhaps unfair: taking off Arda Guler in the middle of the second half and sending on Diamonde on the right wing.
Nobody doubted the Ivorian's ability to help the team. The most expensive signing in Real Madrid's history, worth 125 million euros fixed plus add-ons, exists for moments like these.
The best of the Madrid ranks
Guler was the best of Real Madrid's players on the pitch, especially in attacking terms, which is why the decision to substitute him seemed strange.
The numbers back that up. Guler created the most chances of any Real Madrid player, seven in all, and ranked second among the outfield players for balls won back, with five.
Defensive graft and attacking spark, Guler offered both. Yet the Real Madrid players charged with finishing the attacks, led by Mbappe, failed to make good use of it.
For these reasons, Mourinho admitted the change was hard to explain, though he offered a reason for it: the risk of Guler picking up a second yellow card.
That risk was real. The player was in danger of a booking at the start of the second half, and the Portuguese coach said the Real Betis players would have tried to "hunt him down" from that point on.
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In Seville, that justification held up. In Barcelona against Espanyol, though, Mourinho took Guler off after an hour, just as Real Madrid were looking to secure the win, and after the player had provided a decisive pass to Bellingham.
Even in that match Guler was Real Madrid's best player, as he had been throughout pre-season. But substituting the Turkish star was, just as in Seville, the easiest change.
Mourinho has plenty to juggle as manager of Real Madrid. Some of it plays out purely on the pitch. The rest has its roots in deeper issues.
Take Espi, who adds a fresh dimension every time he gets a chance, yet comes on late, because cutting Mbappe's minutes without a guaranteed win is unthinkable.
Bellingham did not perform well at all in Seville, but he remains Real Madrid's best attacking weapon at the start of the season, which gave Mourinho reason enough to leave him on.
Guler trusts Mourinho
Then there is Vinicius, the most complicated file of all. Xabi Alonso had already tried resting the Brazilian through rotation last season, cutting his minutes when he was off form, and it ended the way it ended.
Vinicius wants to be on the pitch every minute, and talking him out of that will be no easy task. Yet Mourinho did not choose him to come off. He chose Guler.
In fairness, the decision was not entirely bad. Vinicius picked out Espi for an equaliser, ruled out for offside, then won the penalty Mbappe wasted. He gives a lot despite getting little.
For now, Guler keeps his place in the starting line-up in this role, as a false right winger. But the threat of Diamonde looms large, matched only by the size of the fee Real Madrid paid for him, and this is the next battle awaiting Mourinho.
All the while, the Turkish player makes the most of every chance he gets, even when his team-mates cannot match him. He is convinced that working with Mourinho this year can help him develop and make an important competitive leap, and he will prove himself at the first opportunity, as long as Mourinho keeps him on the pitch.