Julián López de Lerma’s side had to withstand two equalisers and a late scare before Yáñez’s superb left-footed finish proved decisive. The victory brought an end to Real Madrid Castilla’s poor run of results and gave the home side fresh momentum.
Ángel Carvajal opened the scoring in the ninth minute after a fine individual run, giving Castilla the reward their early attacking pressure deserved. Álvaro Leiva and Thiago Pitarch also threatened as the hosts controlled much of the first half.
Atletico Madrid B gradually found their way into the contest, with Miguel Cubo going close before a long-range effort from Antal took a deflection off Mario Rivas and beat Sergio Mestre in first-half stoppage time.
The visitors almost went ahead before the interval when David García struck the post, but Castilla regained the lead after the break. Diego Aguado was brought down in the area and converted the resulting penalty in the 61st minute.
There was another twist almost immediately. David García saw his penalty saved by Mestre, but Koke Mota reacted quickest to the rebound and restored parity in the 66th minute.
Castilla refused to let the game slip away. Five minutes later, Yáñez produced the decisive moment with a precise left-footed strike to make it 3-2.
The drama continued into stoppage time. Pol Fortuny had earlier gone close to adding a fourth, while Atlético Madrileño threatened a final equaliser deep into added time. Jorge Castillo’s effort struck the crossbar in the 101st minute, allowing Castilla to hold on.
López de Lerma praised Thiago Pitarch’s performance after the match, highlighting the midfielder’s physical effort and his ability to influence several areas of the game after returning from injury and limited first-team training.
The coach also singled out Jorge Cestero, who returned to the side and impressed in midfield. López de Lerma described him as an important player for the team, pointing to his positioning, ability to retain possession, passing and communication without the ball.
The Castilla coach admitted there were still moments when his team lost control, but viewed their ability to respond after twice being pegged back as an important step in their development.
José Mourinho and his coaching staff were also present at Valdebebas, while Sergio Ramos made a surprise appearance to watch the derby from the stands.
Castilla XI: Mestre; Fortea, Naasei, Mario Rivas, Diego Aguado; Jorge Cestero, Sergio Martínez, Thiago Pitarch, Yáñez, Álvaro Leiva and Ángel Carvajal.
Atlético Madrileño XI: Astralaga; Sergio Díez, Antal, Pablo Pan, Arnau Solà; Edgar, Thiago Helguera, Álvaro Justo; Issiaka Kamate, Miguel Cubo and David García.
Goals: 1-0 Carvajal (9’); 1-1 Antal (45+1’); 2-1 Aguado (61’, penalty); 2-2 Koke Mota (66’); 3-2 Yáñez (71’).