Marin Čilić, born 28 September 1988, is a Croatian professional tennis player. Over the course of his career, Čilić has won 18 ATP Tour singles titles, including a Grand Slam title at the 2014 US Open. His career-high singles ranking is world No. 3, achieved on 28 January 2018. Čilić first came to international prominence by defeating world No. 2 Andy Murray in the fourth round of the 2009 US Open, and then reaching the semifinals at the Australian Open a few months later. He was also runner-up at the 2017 Wimbledon Championships and the 2018 Australian Open, losing to Roger Federer both times. Čilić has reached at least quarterfinal in all four major tournaments, and has made it to at least that stage at 13 different Grand Slams. He is known for his fast serves and powerful ground-strokes.
Čilić started to develop his career at a young age; his first steps of tennis started in Bosnia and Herzegovina. His potential was discovered by local hometown coaches who saw him play and encouraged his move to Zagreb for further training. He was soon befriended by his countryman to be Goran Ivanišević, who introduced him to coach Bob Brett. Čilić turned professional in 2005, and ultimately hired Ivanišević as his full-time coach in 2013. Čilić parted ways with Ivanišević in late July 2016, after advancing to the 2015 Davis Cup semifinals.