Croatia got their World Cup campaign off to the perfect start after 2-0 victory over Nigeria in Kaliningrad on Saturday.
The deadlock was broken in the 32nd minute thanks to an own goal by Nigeria's Oghenekaro Etebo.
Croatia captain Luka Modric, who was named Man of the Match, doubled his team's lead after converting a penalty in the 71st minute.
Both teams are playing in Group D alongside Argentina and Iceland, who played out 1-1 a draw on Saturday.
Croatia will next face Argentina on Thursday, while Nigeria will take on Iceland on Friday.