TERESOPOLIS, Brazil - Brazil playmaker Kaka is not prepared to break the pain barrier in an effort to play against Ecuador in their World Cup qualifier on Sunday. The AC Milan player has struggled with an injury to his left foot since last month and said he had learned his lessons from the 2006 World Cup quarter-finals against France, when he played when not fully fit and Brazil lost 1-0. "In 2006, I played against France with pain in my knee and I regret it," he told reporters on Wednesday. "If I feel any pain which limits me on the field, I won't play. "Every player feels some pain but it can't be pain which limits you." Kaka has been given a 50 percent chance of playing on Sunday in Quito. "I'm much better today, I think there's been a big improvement thanks to the physiotherapy I've done," he said, adding that he hoped to train with a ball on Friday. "I've had some injuries this season which have got in the way, both with Brazil and Milan. When you don't look after an injury properly, you get one after the other. "If I'm not 100 percent, I'm not going to push my luck." Brazil go into Sunday's match second in the South American standings, six points behind leaders Paraguay after 10 rounds.