Croatia centre-back Robert Kovac says he was bewildered at the lack of threat posed by Brazil striker Ronaldo.
The world champions won 1-0, Ronaldo was a shadow of the player who was top scorer four years ago, and after a disappointing display he was replaced midway through the second half by Robinho.
“I don’t know what happened to him,” Kovac told BBC Sport. “He didn’t run and stayed in front of us. He must be tired. He hardly touched the ball.
“It was very easy. I’ve played against him before and it was very difficult. I don’t know what’s happened with him.”
Ronaldo entered the competition with criticism being levelled at him for being overweight.
But Croatia defender Josip Simunic offered some support for the 29-year-old.
“Ronaldo is the most dangerous player in the world,” said Simunic.
“I don’t know what everyone is talking about and I am 100% sure he will score four or five goals in the tournament. Just wait and see.”
Brazil coach Carlos Alberto Parreira and Tuesday’s goalscorer, Kaka, were both supportive of Ronaldo.
Parreira confirmed that the Real Madrid striker would still start their second game against Australia on Sunday.
“Ronaldo has not been playing for the last two months and has had only two friendlies so it was natural he felt a bit heavy as it was very hot, but I’m sure he will improve as the tournament goes on,” he said.
And Kaka added: “Ronaldo has said he has not reached his ideal level of fitness so let’s wait until he improves his performance and is the Ronaldo that we know and like, but yes a little more movement from him would be ideal.”
