|Mourinho speaks to Kaka in Los Angeles before the midfielder flew to Belgium [AFP]
Real Madrid midfielder Kaka has suspected meniscus damage in his left knee and may need surgery.
The Brazilian playmaker, who was plagued with injuries over the past year but recovered to feature at the World Cup in South Africa, had left Real's pre-season training camp in California and flown to Belgium for checks by a specialist, the Spanish Primera Liga club said on Thursday.
"He's a very popular player among his teammates and also a very good player but we want him at 100 per cent so that he is happy," coach Jose Mourinho said at a news conference in San Francisco after Real beat Club America 3-2 in a friendly.
"If we have to lose him for a while it won't be a drama. We have other players and that's that."
Kaka, 28, joined Real from AC Milan at the end of the 2008-09 season for a fee of around $85.3 million.
He made 25 league appearances last term, scoring eight goals.
Real play a friendly against Major League Soccer club LA Galaxy on Saturday in Los Angeles.
Robinho lifts Copa Brasil
Kaka's Brazil teammate Robinho finished his six-month loan stint with Santos on a high note by helping the side win the Copa Brasil on Wednesday and hoped he could extend his stay after settling down in his native country.
Despite losing 2-1 to Vitoria on the night, Santos won the two-leg tie 3-2 on aggregate to lift the nationwide knockout competition for the first time and qualify for next year's Libertadores Cup.
In the last match of his loan spell from Manchester City, Robinho said he would love to stay in Brazil rather than return to the English Premier League side, where he has fallen out of favour with coach Roberto Mancini.
"I hope to continue. My heart is here and I want to stay but I have to talk to my team," he said.
"Santos have brought me happiness and good things."