The 2007 World Player of the Year, who cost Real around 65 million euros (£56m at the time) when they bought him from AC Milan in 2009, will not even be on the bench for Saturday's La Liga game at Granada.
The 30-year-old Kaka was an unused substitute in Wednesday's King's Cup semi-final first leg draw at home to Barcelona and has only been in Mourinho's starting 11 once in La Liga, twice in the Champions League and once in the Cup this season.
The club said on their website that all Mourinho's first-team players, including Kaka, had trained normally on Friday except for Cristiano Ronaldo and Mesut Ozil who worked in the gym.
Some media reports suggested Kaka might return to Milan in January and the honorary president of the Serie A club, former Italian Prime Minister Silvio Berlusconi, said he was optimistic a deal could be done.
However, no agreement was reached before the window closed at midnight on Thursday and Kaka's reported salary of 10 million euros a season represents a significant impediment to any move.
His stint at Real has been disrupted by a number of injuries and when he has played he has only shown flashes of his former brilliance.
Mourinho, who joined Real from Milan's city rivals Inter at the end of the 2009-10 campaign, has generally preferred Germany playmaker Ozil to the Brazilian and the Spanish champions also signed Croatia midfielder Luka Modric in the close season.
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