It’s only the second time the two rivals have played a competitive match on the ATP Tour on clay.
And Cilic’s only win over Federer in their 10 previous matches came back in the 2014 US Open in the semi-finals.
Federer got off to a strong start against the 32-year-old this time around, winning the first set 6-2.
But Cilic fought back early in the second, taking an early break to go up 3-0.
Tensions were rising on the court though with Cilic seemingly unhappy at how long Federer was taking in between points.
The world No 47 pointed out to the umpire that he wanted Federer to be given a warning.
And a time violation warning promptly followed in the fifth game of the set, sparking a furious reaction from the 20-time Grand Slam champion.