Real Madrid midfielder Toni Kroos has criticised Jurgen Klinsmann for failing to teach him anything during his time in charge of Bayern Munich.
Kroos came through the ranks of Bayern's youth academy, joining the club from Hansa Rostock in 2006. He soon made a name for himself and debuted as a 17-year-old in September 2007.
Yet when Klinsmann was hired to replace Ottmar Hitzfeld after that season, Kroos had difficulties earning minutes under the new boss and joined Bayer Leverkusen on loan in 2009. He flourished there once Jupp Heynckes joined the club in the summer.
Looking back on a number of his coaches during his career in an interview with Die Zeit, Kroos did not have any kind words for the current United States manager.
"During his time at Bayern I personally missed everything: An idea of how to play football, adequate communication -- and success," the midfielder said.
Klinsmann coached Germany to a third-placed finish at the 2006 World Cup which they hosted, beginning an era of success that culminated with the 2014 World Cup win under Klinsmann's former assistant Joachim Low.
But asked if Klinsmann played a major role in Germany's development that led to winning the World Cup, Kroos said: "It's not true."
Kroos, who called Heynckes his "most important coach," was called back to Bayern in the summer of 2010, where Louis van Gaal started his second season at the club.
Of the current Manchester United manager, Kroos said: "From his idea of football, he's an absolute top coach. I'll leave it open whether it suited [Bayern] all the time. But he had a concrete idea. And he stuck to it, definitely!"
In 2014 Kroos left for Real Madrid, where Carlo Ancelotti had just won the Champions League but departed after last season.
"He was able to mix the success factors the best: The tactical idea, the human component, which especially at Real Madrid is not easy," Kroos said.
"When he left everyone was sad. Also those who did not play and could have had every reason to criticise him for that. Not a single negative word was said. That's extraordinary."
Although he's since moved to Spain, Kroos also praised Bayern's current boss, Pep Guardiola.
"He has been the best coach I've ever had in terms of his idea of football, the plan on how to play an opponent, and how to present solutions to his own team," Kroos said.