The team sheet handed to the media an hour before Real Madrid's friendly against Fiorentina in Austria told no lies. Trent Alexander-Arnold lined up at right-back, with Denzel Dumfries set to play ahead of him as a winger.
Behind that arrangement, though, lay a tactical plan Mourinho had been keeping to himself. It only surfaced once the match kicked off: a third midfielder in attack, and Arnold was the man.
According to the Spanish newspaper "As", the Englishman offered a triple threat in the 2-2 draw in Klagenfurt. He remained a full-back, since he clearly still occupies the position. He stayed a set-piece specialist, his superb touches as sharp as ever. And now he has become an option for building play too.
Mourinho's plan came into full view after Endrick's goal put Real Madrid 1-0 up. Arnold was the only player the coach summoned to the touchline.
One minute and 29 seconds those instructions lasted. In that time Mourinho spelled out the spaces he wanted Arnold to attack with passes that split the lines.
This echoed what Huijsen offered at the Club World Cup. Arnold would defend in the full-back role, but the moment Real Madrid won the ball he drifted into central areas, opening up more passing lines than Valverde and, in particular, more than Camavinga, who once again failed to convince.
Reading Arnold as a midfielder reveals extra jobs he can do. It also lays bare the fact that Mourinho is short of a player better equipped than Valverde or Camavinga to build with the ball in midfield, all the more so because Camavinga is essentially filling Tchouameni's role on a temporary basis.
Nobody needs telling that this role, blending link-up, control and orchestration, is the hallmark of Rodri.
That plan, the signing of Rodri, has gone into a temporary freeze, "As" reported, despite the green light from the club president at the start of the week.
Right now the focus falls on wrapping up the deal for Diomande before turning to the world champion's file.
City are applying no pressure to hurry things along, while Rodri himself feels the process is heading in a positive direction.
Mourinho, meanwhile, refuses to sit still, because that is not in his nature. The clearest proof is his hunt for answers among the players he has at Valdebebas, and Arnold is one of them while the Rodri saga awaits its final verdict.