Toni Kroos has gone on to be a vital piece of Real Madrid's success since joining the club in 2014.
Bayern Munich's former Sporting Director, Matthias Sammer, has admitted that it was a mistake for the German side to sell Toni Kross to Real Madrid in 2014.
However, the former Borussia Dortmund midfielder - who was the last German player to win the Ballon d'Or - also claimed that decision to swap Bavaria for Madrid has worked out well for the 28-year-old midfielder.
"Sometimes there are situations that you have to analyze honestly in retrospect," Sammer told German publication Sport Bild - who, for this week, have Kroos as a guest editor.
"Who can say they have done everything right in life? Maybe Bayern Munich would have won the Champions League more often with Toni or at least reached the final.
"I can say today that, in my role, it was a mistake to let Toni go. I was sitting on Toni's couch trying to change his mind.
"I've been able to work with him for a long time and have known him since he was 16 or 17.
"His departure didn't shake Bayern, but when you talk about whether it was good or bad to let Toni go, you have to say it was bad, very bad," he added. "But for Toni's personal development and value, the change was definitely the right one."
Despite spending the last four years at the Santiago Bernabéu, Kroos has still made more career appearances for Bayern Munich than Real Madrid, with his tally of 11 winners medals across a number of competitions for the Bavarians also higher than the 10 titles that the coveted midfielder has won with Los Blancos.