Marin Cilic defended his title in Zagreb defeating first-time finalist Michael Berrer 6-4, 6-7(5), 6-3 in the final.
It was croatian's fifth career ATP title.
In January Marin also successfully defended his title in Chennai.
Cilic now holds an impressive 15-1 record this season.
After reaching his first Grand Slam semi-final at the Australian Open the 21 year old entered Top 10 players and now stands 10th place in the ATP Ranking.