Real Madrid has stepped up its interest in Borussia Dortmund's defender, German international Nico Schlotterbeck. According to reports, the Madrid club has already made contact with his agents while it assesses the state of its defence - and behind the whole operation, it's claimed, is the new-old coach José Mourinho.

The reason for the rush is clear. David Alaba is leaving on a free transfer, and Éder Militão keeps battling injuries. When two experienced defenders drop off your books in the same summer, waiting becomes a luxury not even Real can afford.

At 26, Schlotterbeck comes with numbers that explain why it's him they want. Last season in the Bundesliga he won 63 percent of his aerial duels and 61 percent on the ground, with 11 clean sheets in 28 appearances, plus five goals scored - a rarity for a central defender. With the ball at his feet he plays as a link, not just a destroyer.

There's only one obstacle, and it's called the clause. Dortmund extended his contract in April until 2031, but built into the same contract a release clause of 50 to 60 million euros - low enough to leave a door open, high enough not to sound cheap. Dortmund rarely sells, but when it builds in a number like that, it's a message in itself.

For now the player says he's focused only on the World Cup with Germany, which is the standard sentence in situations like this. The negotiations will, as usual, run quietly behind the scenes while everyone is officially silent.