The 71-year-old man, who cannot be named to protect the teenager’s identity, pleaded not guilty to two counts of rape when appearing in the Tonga Regional Court on Thursday.
He is accused of raping his granddaughter in 2010.
He told the court on Thursday that he would never rape his granddaughter.
“I was in Pretoria on the date you mention that the first incident took place. On the date of the second incident I was in jail after being arrested for the first incident,” said the pensioner, who is also visually impaired.
The man told the court that if he longed for sex he would have asked his own wife or raped his daughter instead.
“If I was longing for sex, why didn’t I rape my daughter because she is older than my granddaughter, who is very young? I didn’t rape her, she is lying,” he said.
When State prosecutor Thulani Msibi asked him if he had any idea why his wife, daughter and granddaughter would accuse him of rape, he said he refused to allow his daughter to move back into their house after she separated with her husband.
The complainant testified that her grandfather first raped her when she went to give him his medication for a chronic disease that was not mentioned in court.
She said she was raped again a year later.
Magistrate Edgar Moletsane postponed the trial to February 13.
The accused is out on R1000 bail.