Home favourite Marin Cilic can win a fourth Zagreb Indoors title when the tournament gets under way in Croatia on Monday.
The world number 37 suffered a disappointing Australian Open campaign, bowing out to Gilles Simon in the second round, but will return to his native Croatia eyeing a fourth win in six years at the ATP 250 Series event.
Cilic, a winner in 2009, 2010 and 2013, clinched the title last year with a 6-3 6-1 victory over Jurgen Melzer and will begin his defence against compatriot Mate Delic - a 20-year-old wildcard.
The number five seed has the chance to overtake coach and former world number two Goran Ivanisevic in terms of ATP titles won in Croatia with victory in Zagreb, after Ivanisevic picked up four winner's medals in his homeland.
"Goran is an excellent coach. He passes everything he knows on to me. We have had super preparations and my inner feeling is that I play better than before. All I have to do now is demonstrate this in the matches," Cilic told the tournament's official website.
"(Ivanisevic's record) will not be an additional motive for me. Naturally, it would be nice to raise the winner's trophy again. But, our main goal in this season is to achieve the best possible results at Grand Slam tournaments and at ATP Masters Series."
World number 12 Tommy Haas will make his debut in Zagreb as top seed, having recovered from the shoulder injury that forced him to retire during his first-round clash with Guillermo Garcia-Lopez at the Australian Open.
Mikhail Youzhny and Ivan Dodig, both former winners of the competition, are seeded second and fourth respectively, although two of the world's top 20 have been ruled out due to injury.
Croatian Milos Raonic, number 11 in the world, misses out with an ankle complaint, while Grigor Dimitrov cited his need for rest and recovery as his reason for withdrawal, having suffered a recurring leg injury.
Dimitrov, who reached his first grand slam quarter-final in Melbourne, explained his decision, as he said: "I am very disappointed that I won't be able to compete at PBZ Zagreb Indoors this year.
"The accumulations of matches in Australia and a leg injury makes necessary to give my body a rest to recover."
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