#4. Marin Cilic
The Croat has surely been his country’s best tennis player since the playing days of his current coach Goran Ivanisevic. Ever since returning from a suspension in 2014, Cilic has been playing some of the best tennis of his career which includes winning the 2014 US Open and three consecutive quarter-finals at the Wimbledon with the most recent one witnessing him put up a tough fight against Roger Federer before losing in five sets.The 6ft 6in Croat’s Olympics hasn’t been very good as he has been shown the door in the second round in his previous two appearances at the Olympics at Beijing and London. However, Cilic’s form has improved a lot in the last four years and he will surely be a player to look out for at Rio and will be looking to eclipse or even better his coach’s performance at Barcelona in 1992 where he won the bronze medal.Out of the World No. 12’s 14 ATP singles titles, 12 of them have come at hard courts and all four of his wins against the Big Four have come at hard courts in addition to his only Grand Slam title. Hence, Cilic will surely be a player to be wary of and is bound to give the likes of Federer, Djokovic, Murray and Nadal a run for their money.