![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
![TENNIS on X: "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" / X TENNIS on X: "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" / X](https://pbs.twimg.com/media/DgPToHxUcAE-MV1.jpg:large)
TENNIS on X: "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" / X
![Image of NICOLAS KIEFER. - Kiefer, Nicolas - Tennis Player, Germany - Looking Round - 11.04.2008 No-commercial-use! Not-available-for-Axel-Springer! *** Local Caption *** 00978761. Public Address - Ullstein Bild / Granger, NYC -- Image of NICOLAS KIEFER. - Kiefer, Nicolas - Tennis Player, Germany - Looking Round - 11.04.2008 No-commercial-use! Not-available-for-Axel-Springer! *** Local Caption *** 00978761. Public Address - Ullstein Bild / Granger, NYC --](https://www.granger.com/wmpix/age/ull/0261878-NICOLAS-KIEFER-Kiefer-Nicolas---Tennis-Player-Germany---looking-round---11042008-No-commercial-use-Not-available-for-Axel-Springer--Local-Caption--00978761-Public-Address---ullstein-bild--Granger-NYC----All.jpg)