KOENIGSTEIN, Germany, June 15 - Ronaldo insisted on Thursday he "felt fine" and was looking forward to Brazil's next World Cup match after an illness scare.

The 29-year-old striker, who scored both goals in Brazil's 2-0 World Cup final win four years ago over Germany, was taken to hospital after complaining of dizziness and headaches on Wednesday.

It recalled memories of 1998 when he fell victim to a mystery ilness hours before Brazil's 3-0 World Cup final defeat by France.

"I felt quite sick during the day off (Wednesday) and at about three o'clock in the afternoon the doctor decided to take me to hospital just to make sure there was no serious illness or anything," he told reporters on Thursday.

"I went to hospital and did a series of tests. They didn't find anything abnormal.

"Today I feel fine. I feel fairly relaxed. It's nothing serious. I've been treated. Today I had a session in the gymnasium and I'm just thinking about the game against Australia."

Ronaldo was booed by Brazil fans after a lack-lustre performance against Croatia in their opening Group F 1-0 win and was substituted.

"To be sincere I wasn't happy in my performance against Croatia but the most important thing was that we won," Ronaldo said.

"In the next game I hope to do things a bit better."

Brazil play Australia in their next match in Munich on Sunday. Japan complete the group.