Club captain Sergio Ramos has reportedly threatened to walk out on Real Madrid if Jose Mourinho returns as boss at the end of the season.
Mourinho has been strongly tipped as a contender to succeed Santiago Solari, who was only placed in permanent charge last month.
The Portuguese, sacked by Manchester United nine days ago following the Red Devils' worst start to a league campaign in 28 years, has previously spent three years in the Bernabeu dugout.
According to Mundo Deportivo, however, Mourinho's proposed return to the Spanish capital may be blocked by Ramos, as the long-serving defender will not stay at Madrid if the ex-United boss is appointed.
Ramos fell out with Mourinho before the 55-year-old left Los Blancos in 2013 and recently said that Madrid do not need another new manager.
Mourinho won one La Liga title and one Copa del Rey during his time at the Bernabeu.