Manchester City manager Pep Guardiola is reportedly angry with Leroy Sane over the winger's decision to ignore the club's medical advice.
Sane is expected to miss a large chunk of the new season after damaging his ACL during the Community Shield and subsequently undergoing surgery on the problem.
Man City were understood to be keen to send the 23-year-old to Ramon Cugat, who has previously conducted operations on Benjamin Mendy and Kevin De Bruyne.
However, Sane instead opted to use Professor Christian Fink, who is favoured by the German FA as well as Bayern Munich - a club with whom Sane was heavily linked this summer.
The Mirror reports that Guardiola is unhappy with Sane's decision, which was made due to a desire to prove his fitness to national team boss Joachim Low ahead of Euro 2020.
The Germany international is expected to be sidelined until March, leaving him around two months to prove his fitness before the season ends.