![Ivo Karlovic, of Croatia, serves to Andrey Rublev, of Russia, during the first round of the US Open tennis championships, Monday, Aug. 30, 2021, in New York. (AP Photo/John Minchillo Stock Photo - Ivo Karlovic, of Croatia, serves to Andrey Rublev, of Russia, during the first round of the US Open tennis championships, Monday, Aug. 30, 2021, in New York. (AP Photo/John Minchillo Stock Photo -](https://c8.alamy.com/comp/2MDPBNC/ivo-karlovic-of-croatia-serves-to-andrey-rublev-of-russia-during-the-first-round-of-the-us-open-tennis-championships-monday-aug-30-2021-in-new-york-ap-photojohn-minchillo-2MDPBNC.jpg)
Ivo Karlovic, of Croatia, serves to Andrey Rublev, of Russia, during the first round of the US Open tennis championships, Monday, Aug. 30, 2021, in New York. (AP Photo/John Minchillo Stock Photo -
![Ivo Karlovic becomes oldest ATP winner in 37 years with success in Rhode Island | Tennis News | Sky Sports Ivo Karlovic becomes oldest ATP winner in 37 years with success in Rhode Island | Tennis News | Sky Sports](https://e0.365dm.com/16/07/2048x1152/ivo-karlovic-backhand_3746700.jpg)
Ivo Karlovic becomes oldest ATP winner in 37 years with success in Rhode Island | Tennis News | Sky Sports
![Happy 41st Birthday to one of the greatest servers tennis has ever seen, Dr. Ivo Karlovic! : r/tennis Happy 41st Birthday to one of the greatest servers tennis has ever seen, Dr. Ivo Karlovic! : r/tennis](https://external-preview.redd.it/Kg_m2F7YjRyOYbzzXOYc4Yo8KMpHSZnzBkAYAq8CAKM.jpg?auto=webp&s=66d555fa2fe64dff39ff5db8aad4c0e1adb10d1d)
Happy 41st Birthday to one of the greatest servers tennis has ever seen, Dr. Ivo Karlovic! : r/tennis
![Ivo Karlovic of Croatia returns a shot during his tennis match against John Isner of the United States during the U.S. Men's Clay Court Championships at River Oaks Country Club on Friday Ivo Karlovic of Croatia returns a shot during his tennis match against John Isner of the United States during the U.S. Men's Clay Court Championships at River Oaks Country Club on Friday](https://c8.alamy.com/comp/2P77NF4/ivo-karlovic-of-croatia-returns-a-shot-during-his-tennis-match-against-john-isner-of-the-united-states-during-the-us-mens-clay-court-championships-at-river-oaks-country-club-on-friday-april-8-2011-in-houston-texas-karlovic-won-7-6-2-6-7-2-7-6-9-ap-photoaaron-m-sprecher-2P77NF4.jpg)
Ivo Karlovic of Croatia returns a shot during his tennis match against John Isner of the United States during the U.S. Men's Clay Court Championships at River Oaks Country Club on Friday
![Ivo Karlovic, of Croatia, celebrates after upsetting Roger Federer, of Switzerland, during a match at the Western & Southern Financial Group Masters tennis tournament, Thursday, July 31, 2008, in Mason, Ohio. Karlovic Ivo Karlovic, of Croatia, celebrates after upsetting Roger Federer, of Switzerland, during a match at the Western & Southern Financial Group Masters tennis tournament, Thursday, July 31, 2008, in Mason, Ohio. Karlovic](https://c8.alamy.com/comp/2P9TKM8/ivo-karlovic-of-croatia-celebrates-after-upsetting-roger-federer-of-switzerland-during-a-match-at-the-western-southern-financial-group-masters-tennis-tournament-thursday-july-31-2008-in-mason-ohio-karlovic-won-7-6-8-4-6-7-6-7-ap-photodavid-kohl-2P9TKM8.jpg)
Ivo Karlovic, of Croatia, celebrates after upsetting Roger Federer, of Switzerland, during a match at the Western & Southern Financial Group Masters tennis tournament, Thursday, July 31, 2008, in Mason, Ohio. Karlovic
![Interview: Ivo Karlovic, 39-year-old tennis veteran, on his YouTube lessons, Twitter humour and more Interview: Ivo Karlovic, 39-year-old tennis veteran, on his YouTube lessons, Twitter humour and more](https://s01.sgp1.cdn.digitaloceanspaces.com/article/109930-wpesrbfsev-1546770507.jpg)