Alexander Zverev reacts in his third round match against Hyeon Chung of Korea on day six of the 2018 Australian Open at Melbourne Park on January 20, 2018 in Melbourne, Australia.

In this handout provided by Tennis Australia, Alexander Zverev of Germany holds a Wombat during day three of the 2018 Australian Open at Melbourne Park on January 17, 2018 in Melbourne, Australia.

Alexander Zverev of Germany reacts after missing a shot in his singles match against Thanasi Kokkinakis of Australia on day seven during the 2018 Hopman Cup at Perth Arena on January 5, 2018 in Perth, Australia.

Jack Sock of the United States celebrates victory in his Singles match against Alexander Zverev of Germany during day five of the Nitto ATP World Tour Finals at O2 Arena on November 16, 2017 in London, England.

Alexander Zverev Jr. of Germany reacts against Darian King of Barbados during their first round Men's Singles match on Day One of the 2017 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2017 in the Flushing...More

Alexander Zverev of Germany reacts after defeating Roger Federer of Switzerland 6-3, 6-4 in the final during day ten of the Rogers Cup presented by National Bank at Uniprix Stadium on August 13, 2017 in Montreal, Quebec, Canada.

Alexander Zverev of Germany celebrates after beating Novak Djokovic of Serbia during the final of The Internazionali BNL d'Italia 2017 at Foro Italico on May 21, 2017 in Rome, Italy.

Alexander Zverev of Germany celebrates match point during the men's semi-final match against John Isner of USA on Day Seven of the Internazionali BNL d'Italia 2017 at Foro Italico on May 20, 2017 in Rome, Italy.

Alexander Zverev of Germany celebrates with Bavarian leather pants after winning his finale match against Guido Pella of Argentina of the 102. BMW Open by FWU at Iphitos tennis club on May 7, 2017 in Munich, Germany.