Cuba's acting President, Raul Castro, has told university students he has no intention of imitating the leadership style of his older brother Fidel.
Raul Castro did not mention his brother's health
Mr Castro said Fidel - who is said to be recovering from intestinal surgery - was "irreplaceable".
Raul Castro said he was delegating more responsibility and giving fewer speeches than Fidel.
Fidel Castro,80, has not been seen in public since his July surgery, fuelling speculation about his condition.
Allies of the man who has ruled Cuba for more than 47 years have dismissed rumours that he is suffering from cancer.
Cubans have been told that details of the ailment will be kept secret to prevent the nation's enemies from taking advantage of them.
During his speech on Wednesday, Raul Castro, 75, did not mention his brother's health.
He told the audience of university students that Cuba's communist system would continue with or without Fidel.
Fidel's designated successor, who is also defence minister, said Cuba was at a historic moment.
"I say historic because, like it or not, we are finishing the fulfilment of our duty and we have to give way to new generations," he said.
"Fidel is irreplaceable, unless we all replace him together."