Ivo Karlović is a Croatian tennis player. He has won four ATP singles titles: three in 2007 and one in 2008. Karlović is the tallest player ever on the ATP Tour at 208 cm (6 ft 10 in). He is a serve-and-volleyer, has held the record for the fastest serve recorded in professional tennis, measured at 251 km/h (156 mph) and is considered one of the best servers on tour. His height enables him to serve with high speed and unique trajectory.