"After they scored on us, we were emotionally broken," Sampaoli said. "I had a lot of hope. I am extremely hurt by this defeat, but I probably didn't understand the match the way I should have."

And it got worse as Argentina crumbled, frustrated by the Croatian defense. Modric scored with a hooking shot in the 80th and Ivan Rakitic added the third in stoppage time.

Croatia frustrated Argentina throughout the match and never gave Messi space to operate.

"Argentina wasn't confused. We were excellent," Croatia coach Zlatko Dalic said. "We beat a great Argentina with the best player in the world playing, Messi."

Croatia, which reached the 1998 World Cup semifinals but has not advanced past the group stage since then, will face Iceland on Tuesday in Rostov-on-Don.