Ivo Karlović (Croatian pronunciation: [ǐːʋo kâːrloʋitɕ]; born 28 February 1979) is a Croatian former professional tennis player. His height of 211 cm (6 ft 11 in) makes him the joint-tallest ranked tennis player in history (along with Reilly Opelka). He won eight ATP Tour singles titles between 2007 and 2016. He was a serve-and-volleyer and officially held the record for the fastest serve recorded in professional tennis, measured at 251 km/h (156 mph), before being officially surpassed by John Isner in 2016. He was considered one of the best servers on tour, and held the record for career aces from 1991 onwards with 13,728 (not including Davis Cup) before the record was broken by Isner on 1 July 2022. This makes him one of only five players since 1991 to surpass 10,000 aces. His height enabled him to serve with high speed and unique trajectory.
Karlović played his first junior match in April 1995 at the age of 16 at a grade 3 tournament in Croatia. He played only eight tournament throughout his junior career (four singles and four doubles). In singles, he defeated a 15-year-old Marat Safin at the 1995 Junior Davis Cup. In doubles, he was known for partnering future world No. 3 Ivan Ljubičić on numerous occasions.
Karlović ended his junior career with no ranking in both singles or doubles. He had an overall win–loss record of 3–5 in singles and 5–3 in doubles.
Although not turning pro until 2000 at the age of 21, Karlović played his first ITF futures event in June 1998 and made two finals in August 1998 and September 1999, losing both. He played his first Challenger event in December 1999.
Karlović debuted for the Croatian Davis Cup team in 2000 against Ireland, where he won the dead rubber. Karlović appeared in a starting line-up for the first time in 2002 against Argentina in Buenos Aires, but he lost to Juan Ignacio Chela in the second rubber and to Gastón Gaudio in the fifth and decisive rubber. He has posted a 4–2 career record (2–2 in singles) in three ties since 2000.
Karlović caused a major upset at Wimbledon when he beat defending champion Lleyton Hewitt in his first match in a Grand Slam tournament. As of 2015, Karlović remains the only player in Open tennis history, and only the second player after Charlie Pasarell, to defeat the defending Wimbledon men's singles champion in the first round. He finished the 2003 year in the top 100 and as the Croatian No. 3, behind Ivan Ljubičić and Mario Ančić. He also averaged an ATP-best of 17.6 aces per match. He continued his success during the 2004 season, winning at Calabasas, California. He reached the round of sixteen in several tournaments, including Wimbledon.
In 2005, Karlović reached his first ATP final at the Queen's Club Championships, defeating Lleyton Hewitt and Thomas Johansson along the way. In the final he lost to Andy Roddick. There were no breaks of serve in the match. Afterwards, Roddick said Karlović's serve is "probably the biggest weapon in tennis... you don't really get a feel for it unless you are on the other side. It was not fun at times."
At the 2005 US Open, Karlović lost to eventual runner-up Andre Agassi in three tiebreakers. On 19 October 2005, he finally defeated Roddick in the Madrid Masters event. In November 2005, he was a member of the Croatian team that won the Davis Cup. He did not play in the finals, but played in a semifinal dead rubber.
2006: Breaking into the top 50 in singles and doubles
On 26 February 2006, he won his first ATP Doubles Tournament with South African Chris Haggard, beating James Blake and Mardy Fish in the 2006 Regions Morgan Keegan Championships and the Cellular South Cup, Memphis, USA. On 27 February, he reached a career high of No. 47 in doubles and on 8 May he also reached the top 50 in singles.
2007: First ATP title and breaking top 30
Karlović and Roger Federer were the only players who won titles on three different surfaces during the 2007 season.
At age 28, he won his first ATP singles title at the 2007 U.S. Men's Clay Court Championships in Houston, Texas, defeating Mariano Zabaleta in the final. On 29 May 2007 at the French Open, he defeated eighth seed James Blake in the first round. In the next round he lost to Jonas Björkman in five sets.
On 23 June 2007, he won his second title of the year and his career at Nottingham, the last grass tune-up before Wimbledon, defeating seventh seed Stanislas Wawrinka, Gilles Simon, Juan Martín del Potro, second seed Dmitry Tursunov (a match played on indoor hard courts due to torrential rain), and Arnaud Clément. Despite a first-round loss at Wimbledon, he rose to No. 40, making his top-40 debut.
On 14 October 2007, he won his third title of the year by taking the Stockholm Open, defeating former Australian Open champion Thomas Johansson in three sets in the final. Earlier, Karlović had yet again met Frenchman Arnaud Clément in his quarterfinal, the pair having met five times that year alone, including in the final of Nottingham, where Karlović secured his second career title. Karlović edged past his rival after saving a match point in the final-set tiebreak, and then went on to defeat German No. 1 Tommy Haas in the semifinals.
2008: Fourth ATP title and breaking top 15
At the 2008 Australian Open, Karlović entered the men's doubles tournament with 6 ft 9 in (2.06 m) John Isner, making them the tallest doubles pair in history. Despite losing in the first round, Karlović said "It was a lot of fun. We will win together next time."
Karlović defeated world No. 1 Roger Federer in the third round of the Cincinnati Masters on 31 July 2008. This was his first victory in seven matches against Federer. It was this loss which caused Federer to lose his No. 1 ranking to Rafael Nadal. Karlović then advanced to the semifinals where he lost to eventual champion Andy Murray. This was his career-best result in a top-level tournament.