BERLIN, June 12 - Brazilian midfielder Kaka, who played 18 minutes at the 2002 World Cup, is relishing the chance to make a much bigger impact this time.

Kaka is now part of Brazil's so-called Magic Quartet and is set to play a major role as the defending champions launch their assault on a sixth world title on Tuesday against Croatia.

"I'm very happy to be involved and this time to be able to play and take part more directly," said the AC Milan player, whose only appearance four years ago was as a substitute against Costa Rica.

"It was wonderful for me to be involved last time at such a young age but this time it's a new responsibility."

"I think I've prepared well, I feel fit and ready to go and I think I can have a good World Cup."

Brazil kick off against Croatia on Tuesday before facing Australia and Japan.

The 24-year-old's pace, energy and incisive passing in midfield have make him arguably Brazil's most important player after Ronaldinho.

He has also made light of his 2003 move to Italy, a country where many foreign players have trouble adapting.

Kaka has been a regular since 2003 when he came on as a substitute to score the winning goal away to Colombia in the first goal of their qualifying campaign for Germany.

He added that too much emphasis was being placed on the quartet, which also includes Ronaldo, Ronaldinho and Adriano.

"The whole team is ready for the game, not just the quartet, but also the midfield and the defence," he said.