Coach Carlo Ancelotti said the Brazilian striker still needed more time to recover.
‘He cannot withstand 15 minutes on the pitch in his condition as it is now,’ Ancelotti said here Wednesday.
‘We made the decision at a meeting this morning with him and doctors to leave him from the semi-final. But I believe he will recover and be ready to play sooner or later. In any case, he will have ample time until Sunday.’
Milan are expected to defeat Urawa and confront Argentina’s Boca Juniors in Sunday’s final of the tournament of continental champions, assuming Boca beat unfancied Etoile Sahel of Tunisia in their own semi-final later Wednesday.
Ronaldo had joined training Tuesday for the first time since the European Champions League winners arrived here last week.
‘I feel fine,’ he told reporters before working out alone with 30 minutes of light jogging.
Asked then about his chances of playing in the final, he said: ‘I will see. I will be trying in the next days.’
Ronaldo has played in just one match this season, starting against Cagliari two weeks ago on his return from a thigh problem.
He then injured his calf in training, and travelled here in pain with the rest of the team.