Roger Federer is a relentless title-winning tennis player.

He's admired for his on-court elegance and his off-court demenour.

But he's not always polite. There are also times he's smashed his racket, sworn at an umpire, and even yelled at the crowd.

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Roger Federer. We all know him as a 20-time Grand Slam champion.

The 38-year-old is hailed by his peers as the "greatest of all time," he is renowned for his elegant technical skill, and has a friendly attitude when it comes to the press and social media.

But though he is seen as polite and graceful, you may not realise he also has a history of swearing, smashing tennis rackets, and yelling at the crowd to just "shut up."

Read more: The incredible life of Roger Federer, the highest-paid tennis player in the world

In this list, we highlight 10 times the normally mild-mannered Federer went wild in the middle of a tennis match — the times he broke his own equipment in a fit of rage, and the times he landed fines for his sometimes impolite ways.

Let's start at the very beginning, shall we?