Tuchel's reputation continues to grow after an impressive first season at Westfalenstadion in 2015-2016, guiding Dortmund to second in Bundesliga and a berth in the DFB-Pokal final as it returned to the UEFA Champions League.

The 43 year-old - out of contract in 2018 - has Dortmund challenging both domestically and in Europe again this season, which Watzke believes has alerted LaLiga giant Madrid - reportedly pursuing star forward Pierre-Emerick Aubameyang.

"I have a good relationship with Real Madrid and I believe that they are tracking him [Tuchel]," Watzke told German TV channel ZDF.

"After the season Thomas had with us, Real have taken account of what a first-class coach we have.

"Florentino Perez [Madrid president] has not asked me about him yet. We are not worried about losing him if Madrid wanted him now. Thomas Tuchel has a contract with Dortmund.

"His situation is different to that of a player. A player at the age of 28 or 29 might only have three years in him and could ask us not to deny him such a move. Thomas is still a very young coach, he could still coach at whatever club he wants for 20 years or so."