With three wins out of three, they stand top with just the bottom two teams - Kazakhstan and Australia - left to play.
Paulo Obradovic helped himself to two goals, while Damir Buric, Niksa Dobud and Maro Jokovic netted one each in the contest.
Spain showed their strength in depth as they overcame Australia 13-9.
David Martin, Albert Espanol and Felipe Perrone each netted a brace for Spain, while Billy Miller was on target five times for the Australians.
Greece made light work of Kazakhstan, wrapping up an 11-4 success.
The Kazakhs slipped to their third successive defeat of the Games, while the Greek side claimed their second win out of three Group A matches.
Montenegro, meanwhile, clawed back a hard-fought 11-11 draw against Group B rivals Serbia in an enthralling clash - setting up an intriguing second week in the competition.
Serbia looked to be in control as they led for the majority of the match, but Montenegro kept pegging them back, and crucially clinched an equaliser in the very last minute of the game.
Reigning Olympic champions Hungary claimed their first points in the tournament following a 17-15 win over Romania.
Norbert Madaras fired home five for the eventual winners, while Norbert Hosnyanszky and captain Peter Biros netted hat-tricks.
Great Britain slipped to a third successive defeat, going down 13-7 against the USA.