![TENNIS on Twitter: "Nicolas Kiefer shares an epic #ThrowbackThursday photo of a very young, long-haired Federer, Haas and more: https://t.co/SmCb7RuuBI https://t.co/35jIpPBxHt" / Twitter TENNIS on Twitter: "Nicolas Kiefer shares an epic #ThrowbackThursday photo of a very young, long-haired Federer, Haas and more: https://t.co/SmCb7RuuBI https://t.co/35jIpPBxHt" / Twitter](https://pbs.twimg.com/media/DgPToHxUcAE-MV1.jpg:large)
TENNIS on Twitter: "Nicolas Kiefer shares an epic #ThrowbackThursday photo of a very young, long-haired Federer, Haas and more: https://t.co/SmCb7RuuBI https://t.co/35jIpPBxHt" / Twitter
![Kiefer criticizes Zverev and Thiem: "Questioning whether they have anything other than tennis balls in their heads · tennisnet.com Kiefer criticizes Zverev and Thiem: "Questioning whether they have anything other than tennis balls in their heads · tennisnet.com](https://www.tennisnet.com/fileadmin/_processed_/d/1/csm_nicolas-kiefer_0ba1ca58f3.jpg)
Kiefer criticizes Zverev and Thiem: "Questioning whether they have anything other than tennis balls in their heads · tennisnet.com
![Nicolas Kiefer at the Los Angeles Tennis Open Editorial Stock Image - Image of wide, professional: 11418909 Nicolas Kiefer at the Los Angeles Tennis Open Editorial Stock Image - Image of wide, professional: 11418909](https://thumbs.dreamstime.com/z/nicolas-kiefer-los-angeles-tennis-open-11418909.jpg)