The World No. 6 has had a difficult time on the ATP Tour as of late, suffering a string of early exits over the North American and Asian swings. At the Stockholm Open this week, the Dane lost to Miomir Kecmanovic in the first round.
Recently, Rune did a training week with Becker in Monte-Carlo and has now asked the six-time Grand Slam champion to coach him for a longer period of time.
"I can confirm that I am Holger Rune's coach," Becker told Eurosport Germany's podcast.
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"It makes me a little proud that he asked me. The contact has existed for a long time. Now it was a very good fit," he added.
Becker details approach to coaching Rune
"Holger then invited me to a training week in Monte-Carlo. I also had a long chat there with his mother Aneke and his performance coach Lapo Becherini. The three of us are responsible for Holger from now on. Unfortunately, I can't be at the tournament in Stockholm this week because of previously arranged appointments.
"But I will be there in Basel at the latest, and afterwards, I will play Paris-Bercy with Holger - and hopefully help him to qualify for the Nitto ATP Finals in Turin. That is the big goal and that is the task," Becker explained.
The German former player went on to discuss aspects of Rune's approach to the game that they will work on, highlighting his mentality on his court. He added that this was something he worked on with Novak Djokovic when he coached the World No. 1 from 2013 to 2016.
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"Holger is a rough diamond that needs polishing. I like his emotional outbursts. I have coached a player before, Novak Djokovic, who was sometimes not quite himself on the court, but that is allowed.
"The question is: how quickly do you find your way back into the match, are you focused again? In the end, it's not about sending your mother out of the stands, but winning the match. I love tennis and when one of the best 20-year-olds in the world asks me if I'd like to coach him... anyone who says no doesn't have much to do with the sport.
"Of course, it's all about attitude, even if it's so easy to say that. But it is the main reason why tennis matches are won or lost. For me, it's about: what is Holger's motivation and the reason to go to China, for example. Is it just to win the first round or the tournament, is it for ranking points?
"That has to be discussed and it has to be very clear what the motivation is. I have some ideas on what can be improved. It starts with attitude, mentality, psyche - and I have a little idea about that," he continued.