© Instagram/Nicolas Kiefer & Instagram/Roger Federer

Nicolas Kiefer breaks out his best hat for Roger Federer's volley challenge.

Fans & Players Flock To Federer's Volley Challenge

Football star Toni Kroos also joins the fun 

When Roger Federer issues a challenge, it’s hard not to accept it. Current and former ATP Tour players joined Olympic athletes and eager fans in sporting their best hat to take on his volley challenge.

Federer embraced the #tennisathome campaign with a social media video on Tuesday that showed him hitting rapid fire forehand volleys against a wall while wearing a Panama hat. He asked his followers to reply back with a video of themselves doing the drill so that he could provide tips and encouraged everyone to “choose your hat wisely.”

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It only took 24 hours before former World No. 4 Nicolas Kiefer, Fred Gil and WTA player Sofia Kenin posted videos showing off an array of colourful hats. Real Madrid football star Toni Kroos, Olympic skier Lindsey Vonn and World Cup alpine ski racer Mikaela Shiffrin also made Instagram posts in a bid to get feedback from the 103-time tour-level champion.

Federer, always a man of his word, shared several of the videos on his Twitter account and offered encouragement.

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