The match was played behind closed doors with press access restricted to the first 20 minutes and the club's own television channel cutting its broadcast partway through.
Mourinho named nine of his likely first-choice XI in a side built around a 4-3-3 shape, with Andriy Lunin captaining a back line of Trent Alexander-Arnold, Raul Asencio, Dean Huijsen and Alvaro Carreras, Cestero screening in front of them alongside Eduardo Camavinga and Arda Guler, and Franco Mastantuono, Gonzalo Garcia and academy prospect Gabri Valero making up the front three.
Fede Valverde, only two days into training after returning late, watched from the stands rather than featuring.
The game burst into life inside the first minute when Mastantuono won a penalty, cutting in from the right before going down under a challenge. Guler took the ball from Gonzalo Garcia to take the resulting spot-kick himself but saw his effort saved by Alcorcon goalkeeper Oriol Marti.
The half continued at a lower tempo after that opening flurry, with staff repeatedly shouting "tension" from the touchline throughout the warm-up and early stages as Mourinho stressed intensity as a non-negotiable.
The Portuguese watched most of the session from the bench in a pink tracksuit, only leaving his seat once during the period media were present to issue brief instructions before returning to his position.
Mourinho made wholesale changes at the 70th-minute mark, withdrawing every recognised first-team player and handing an extended run-out to Real Madrid Castilla players. The change paid off five minutes later when the visitors were awarded a second penalty of the afternoon, converted calmly by Yanez despite protests from the Alcorcon bench, proving the difference in a game played under smoke haze from wildfires burning near Avila and in the Madrid region.
Guler was among the more eye-catching performers before his withdrawal, growing into the game after his early penalty miss and dictating set-piece play, while Mastantuono was widely regarded as the standout performer of the opening period. Real Madrid's next pre-season test comes as they continue building towards the new La Liga campaign under Mourinho.