According to Bild, Schlotterbeck has repeatedly told those closest to him how much a move to the Spanish capital appeals. Real Madrid are now planning to act on that intelligence.
The 26-year-old signed a contract extension with Borussia Dortmund until 2031 in April — a deal that simultaneously provided the club with long-term security and gave Schlotterbeck a carefully negotiated route out.
The release clause, worth between €50 million and €60 million, applies exclusively to a small group of non-German clubs, with Real Madrid, Liverpool and Barcelona understood to be among them. Bayern Munich are specifically excluded.
The clause has a hard deadline. Reports from Sport Bild and journalist Florian Plettenberg place its expiry at July 19, the date of the World Cup final. If Madrid are to act, they must do so while Schlotterbeck is still competing at the tournament.
His performances for Germany in North America may prove decisive. German football legend Lothar Matthäus argued publicly that the arrangement is fair to all parties: the player gets his World Cup showcase, Dortmund get their fee, and whichever elite club triggers the clause gets a left-footed, ball-playing centre-back at a defined price.
Madrid's defensive rebuild under incoming manager José Mourinho — due to be officially presented on Wednesday — is substantial. David Alaba is leaving. Raúl Asencio could follow. Éder Militão is injury-prone. Ibrahima Konaté arrives from Liverpool on a free transfer, but the squad still requires reinforcement.
Meanwhile, a separate Dortmund story is developing on the opposite flank. Brazilian right-back Yan Couto has been frozen out at Signal Iduna Park after Julian Ryerson's outstanding season reduced him to a fringe role, and Como have opened negotiations over a possible move.
According to Sky Germany and journalist Matteo Moretto, Dortmund are demanding €20 to €25 million for Couto — a sum Como cannot meet outright. As a result, Sky report that only a loan is realistic for the Italian side, and that scenario is considered workable by Dortmund given Couto's peripheral status.
Couto, 24, joined Dortmund permanently from Manchester City for a total of €25 million in October 2024 after his release clause was triggered from a loan arrangement. He has a contract until 2030 and earns approximately €5 million per season — a wage bill that would stretch even a Champions League-bound Como side to its limits on a permanent deal.
The club managed by Cesc Fàbregas has qualified for next season's Champions League for the first time in its modern history. Playing Champions League football was likely part of the pitch to Couto.
Whether a loan is enough for the player — after having spent much of last season watching rather than playing — is a question only he can answer.