The 3-0 victory over Argentina on Thursday was one of the most compelling performances of the tournament so far, taking the Croatians through to the knockout stages for only the second time and the first since 1998.
Now, Croatia expects this team to at least match the achievements of the celebrated '98 group, which reached the semifinals in its first World Cup before losing to eventual champion France.
The first objective - progressing from the group - has been achieved in Russia.
"We are ecstatic about it (but) ... we should go game by game," Croatia captain Luka Modric said. "Let's not get euphoric. Let's keep our feet firmly on the ground."
It will be hard for Croatians not to start dreaming after Modric's spectacular long-range strike helped humble Argentina, a two-time world champion which has arguably the world's best player in Messi.
Croatia got a lucky break when Argentina goalkeeper Willy Caballero gifted it the first goal with a blunder. But Modric's superb second, and a third from Ivan Rakitic in injury time, sent Croatia through.
"We played a great game, and you need to play a great game to beat a great team," Modric said.
While guarding against complacency, Croatia had so many things to be delighted with.
The defense kept Messi quiet, with the superstar a peripheral figure through much of the game. The midfield, anchored by Modric and Rakitic, is a contender for the best in the tournament. Striker Mario Mandzukic was a constant worry for Argentina's defense. And Coach Zlatko Dalic's tactics were perfect when it came to Messi.
"We were excellent, Dalic said. "We've done a lot of good things.
"From Day 1, I've been trusting my team. Frankly speaking, I did not believe that we would be through after two games, but I did believe we would go through."