Creative midfielder Modric is likely to carry much of Croatia's threat at the global showpiece, starting with Thursday's opener against the hosts.
After a gruelling campaign with Real Madrid where Modric won the UEFA Champions League and the Copa del Rey, he insists he is fully fit going into the World Cup.
"I feel good, I'm healthy and most importantly I have had the right training," he said.
"I got a few days of rest after winning the Champions League and the chance to mentally switch focus to the team.
"I am ready, eager and cannot wait for the first game of the World Cup."
Croatia missed out on the World Cup in South Africa four years ago before bowing out of Euro 2012 at the group stage.
However, with the likes of Modric, Ivan Rakitic and Mario Mandzukic all in good form, Niko Kovac's side stand a good chance of making it to the knockout stages.
"As individuals, we have made a huge step forward and we will see in this tournament how we have progressed as a team," Modric added.
"We played very well at the European Championships two years ago but we lacked a little bit of luck.
"Then we had a lot of problems in qualifying. But I think that in this World Cup we could go far and our first goal is to get to the second round."
