Schalke 04's teenage Wales winger Rabbi Matondo apologised on Wednesday after being photographed wearing a shirt of the German club's arch-rivals Borussia Dortmund in a private training session this week.
Matondo was given a dressing down by Schalke officials after an Instagram post of him training in the shirt in a Cardiff fitness studio caused a social media storm among Schalke fans, whose Ruhr rivalry with Dortmund is long standing.
"I am very sad and disappointed in myself that I have let down everyone who feels connected with Schalke," he wrote on Instagram.
"I was naive and put the jersey on for a private training session. The jersey was from my close friend Jadon Sancho. I only wore it because of Jadon, it had nothing to do with Dortmund," he added.
Schalke had telephoned Matondo after the original picture was posted to register their displeasure.
"He is only 19-years-old but he shouldn't have done that," said club spokesperson Jochen Schneider.
Matondo has been at Schalke since the start of 2019 after previously playing for Manchester City's youth team.
He scored two Bundesliga goals in 20 appearances this season.
(Writing by Mark Gleeson in Cape Town; Editing by Christian Radnedge)
