Kovac, who took over from Igor Stimac in October after Croatia took one point from their last four qualifying games, said the atmosphere in the squad had improved and was confident they would qualify for the 32-nation tournament in Brazil next year.
"The players looked like a disjointed group of individuals and not much of a team when I took over, but the lads are now very positive about our chances and we are convinced we will do what it takes to get the job done," the former international midfielder told Croatian media on Friday.
"As far as the new arrivals are concerned, Males earned his call-up with impressive form for his club and so did his Rijeka team mate Benko.
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"I was a defensive midfielder like Males and I know very well what traits are needed to perform well in that position."
Croatia visit Iceland on Nov. 15 and play them at home in Zagreb's Maksimir stadium four days later in one of Europe's four playoffs for the continent's last remaining berths.
Although Croatia were delighted to be pitted against Iceland in the playoffs, Kovac struck a note of caution and warned that his counterpart Lars Lagerback had a wealth of experience in big events.
"In Lagerback, Iceland have a fantastic coach who's been to five major tournaments," said the 42-year-old Kovac.
"They have a typical northern style, they are disciplined and very direct. Their football is simple and although Iceland often resort to the long-ball strategy, they have some skilled players who can keep it on the ground.
"It's no accident they reached the playoffs and we are up against a physically strong and dynamic team, but if we play to the best of our abilities we should come out on top."
Swede Lagerback guided his native country to two World Cups and as many European Championships before he steered Nigeria through the 2010 World Cup in South Africa.
Croatia finished second in Group A behind Belgium in qualifying, while Iceland clinched the runners-up spot in Group E behind Switzerland.
Goalkeepers: Stipe Pletikosa (Rostov), Danijel Subasic (Monaco), Lovre Kalinic (Hajduk Split)
Defenders: Darijo Srna (Shakhtar Donetsk), Domagoj Vida (Dynamo Kiev), Josip Simunic (Dinamo Zagreb), Vedran Corluka (Lokomotiv Moscow), Dejan Lovren (Southampton), Ivan Strinic (Dnipro Dnipropetrovsk), Gordon Schildenfeld (Panathinaikos), Sime Vrsaljko (Genoa)
Midfielders: Ivan Rakitic (Sevilla), Luka Modric (Real Madrid), Ivan Perisic (Vfl Wolfsburg), Mateo Kovacic (Inter Milan), Milan Badelj (Hamburg SV), Niko Kranjcar (Queens Park Rangers), Mate Males (Rijeka), Ivo Ilicevic (Hamburg SV)
Forwards: Mario Mandzukic (Bayern Munich), Ivica Olic (Vfl Wolfsburg), Eduardo da Silva (Shakhtar Donetsk), Nikica Jelavic (Everton), Ante Rebic (Fiorentina), Leon Benko (Rijeka).
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