Brazil coach Carlos Alberto Parreira insists he has no plans to drop Ronaldo from the World Cup holders' starting line-up to face Australia on Sunday.

The Real Madrid superstar, Golden Boot winner when the samba superstars lifted the trophy in 2002, looked overweight and lethargic in the opener against Croatia on Tuesday night.

But Parreira defended the striker, saying: "I don't agree, our penetration was very good, Ronaldo was very closely marked, as was Ronaldinho and Kaka, and we always found eight players in front of us. Having said that we still had 10 or 12 shots at goal.

"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.

"Ronaldo will start against Australia because he needs to gain pace, and he is a decisive player."

The Brazil coach added the victory had been an essential confidence-booster.

He said: "We climbed the first step today and it was an exceptional result, but we know the performance can and will improve.

"We faced a very good team technically who had been playing together for a long time and they made life difficult for us."

Brazil's matchwinner Kaka admitted the reigning champions were less than convincing.

The AC Milan star struck a brilliant goal to give his team a winning start, but the South Americans only played well in flashes.

Kaka said: "It was essential to win our first match but we all have to improve and that includes myself.

"We have to improve our movement, to be more creative and to mark better.

"We felt a heavy responsibility as it was the first game, and it was against the strongest opponents in our group - we respect Australia and Japan but we are traditionally stronger than them.

"To win like we did is not ideal and we still have to convince and I'm sure the next game will be better as we will not feel under so much pressure."

Kaka admitted Ronaldo's lack of mobility is something that will need to change.

He 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."

Croatia's coach Zlatko Kranjcar claimed his side had outplayed Brazil for much of the match.

Kranjcar said: "I thought it was an excellent game. Croatia lost, but I didn't think we deserved to lose because for most of the time we were the better team and it's a pity we didn't make better use of our opportunity.

"If you make only one mistake against Brazil you will usually lose but it show that we are well-prepared for the next two matches."

Influential captain Niko Kovac went off with bruised ribs and Croatia will have to wait and see whether he will be ready to play the remaining group games.

"He received a blow on the ribs and after the examination we will see whether he can play but we hope it's not going to keep him out of the other matches," said Kranjcar.