Winnie Madikizela-Mandela launched a legal challenge against Mandela's will in October, claiming that the house -- built on a large estate where the revered South African leader is buried -- was acquired by her in 1989 when Mandela was still in prison.
She wants the court to nullify the registration of the Qunu property in Mandela's name.
But the late statesman's executors "have resolved to oppose the claim filed by Mrs Nomzamo Winifred Mandela", said one of the estate's administrators Dikgang Moseneke, who is also South Africa's Deputy Chief Justice.
"The executors are obliged to defend the validity of the will and the wishes of the testator."
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In his will, Mandela left the house in southeastern South Africa to his family trust "for the benefit of the Mandela family and my third wife (Machel) and her two children".
"The Qunu property should be used by my family in perpetuity in order to preserve the unity of the Mandela family," the revered anti-apartheid hero and Nobel peace laureate said.
Last week she questioned why the property was left to Mozambican-born Machel, whom she said already owns "the world in Mozambique".
Winnie was Mandela's second wife and they were married for 38 years.
The couple divorced in 1996 and she was not named in his USD 4.4 million (3.5 million euro) will which was released in February after his death in December 2013.