2014 US Open champion Marin Cilic will be representing Croatia at the Olympic Games for the third time in his career, and the ninth seed has suffered two confidence-shattering five set defeats in recent weeks from being in a commanding two sets to love position.
Grigor Dimitrov has not had a good 2016 campaign on the ATP World Tour either, and the Bulgarian has currently dropped to 34th in the world, which is far from his career high ranking of number eight in the world.
Cilic has recently split from his coach, Goran Ivanisevic, who was instrumental in changing the Croat's game by improving his serve placement and guided him to win his first Grand Slam singles title two years ago.
Dimitrov was a Wimbledon semifinalist in 2014 and since then, the Bulgarian has struggled to live up to expectations, and his tennis has suffered the last two years.
Cilic's Olympic history
The current world number 14 participated in the Beijing Olympics in 2008 and the London Olympics in 2012.
The Croat was 19-years-old at the time of his debut appearance in Beijing, and he defeated Argentine Juan Monaco in the first round, but his tournament was halted in the second round as he lost to Chilean, Fernando Gonzalez, who went on to the gain the silver medal as he lost to former world number oneRafael Nadal in the gold medal match.
Four years later, the Olympics took place on the lawns of Wimbledon and Cilic was seeded 13th. He defeated Austria's Jurgen Melzer in the first round but in his second consecutive appearance at the Olympics, he suffered a second round exit to former world number one and two-time Grand Slam champion, Lleyton Hewitt.
Cilic also represented his country in the doubles event and he paired up with his compatriot, Ivan Dodig, and the unseeded duo reached the quarterfinals but fell to Spain's David Ferrer and Feliciano Lopez who went on to finish fourth in the tournament.
Dimitrov's Olympic history
The unseeded Bulgarian participated in his first Olympic Games four years ago at London in 2012, on his favourite surface on grass. Dimitrov was relatively unknown to the public back then, and he opened his campaign against Poland's Lukas Kubot, who went on to reach the quarterfinals at SW19 a year later. The former top ten player dispatched Kubot 6-3, 7-6 to reach the second round on his debut appearance, however, he fell in straight sets to France's 12th seed Gilles Simon, 6-3, 6-3.
Cilic's notable hard court results
The Croat lost in the third round of the Australian Open to Roberto Bautista Agut in straight sets and suffered a quarterfinal defeat to David Goffin at the BNP Paribas Open at Indian Wells, and a third round loss to Gilles Simon at the Miami Open.
Dimitrov's notable hard court results
The Bulgarian paid for having a low seeding at the Australian Open as he lost to four-time champion Roger Federer in the third round in four sets, and he suffered an opening round defeat to Alexander Zverev in Indian Wells and he reached the fourth round of the Miami Open but lost to Gael Monfils in three sets.
Their history
Cilic and Dimitrov have played each other twice in their careers and both of their meetings have taken place on hard courts. Their head-to-head is tied at one win apiece.
Their first meeting took place in the second round of the Brisbane International in 2014 and Dimitrov was seeded fifth, but Cilic was victorious in two tight sets 7-5, 7-5 to reach the quarterfinals.
The duo's second meeting occurred in the second round of the indoor Masters 1000 event at the BNP Paribas Masters in 2015, and the Bulgarian gained his revenge by dispatching the Croat in two tiebreaks in the French capital.
Who wins?
Cilic is a dangerous threat on hard courts and he can beat anyone on this surface when his game is firing on all cylinders. The Croat's serve out wide and down the T, has become difficult for many players on the ATP World Tour to deal with.
Dimitrov has fantastic movement and his backhand is a dangerous weapon, and he can produce scintillating tennis by showcasing his athleticism as he can engage in long rallies.
The world number 14's movement isn't the best on tour but for his height, Cilic is an exceptional mover on this surface, however, the Bulgarian is a better mover and he can take advantage of this by getting Cilic around the court, and out of his comfort zone as the former US Open champion likes to dictate play from the baseline.
Dimitrov's main problem is his mentality and he has lost plenty of matches that he would have won in 2014.
Whilst both players may not be having the best of seasons in 2016, they are both passionate players and representing their countries at the Olympics will mean a lot to them.
This match will follow the USA's Madison Keys and Danka Kovinic of Montenegro encounter on Court One, and the winner of this tight affair will play Moldova's Radu Albot or Russia's Teymuraz Gabashvili in the second round.
Prediction: Cilic in straight sets.