Homar said the world number two, who beat top-ranked Novak Djokovic to win his second US Open title on Monday, "always liked anything that was round". (Agencies)
"He started playing with balls in the hallway of his home before he learned to walk," Homar said, adding things often got broken by accident.
"He loved playing football and he was always excited when Saturday came around," added the 82-year-old. "He liked football just as much as tennis."
Homar remembered how her son Toni, who has coached his nephew to 13 grand slam titles, rang her one day and told her to come and watch her grandson.
"I remember one day Toni called me and said 'you have to come and see him'," she said after watching Nadal's victory at Flushing Meadows on television with members of her family.
"I can't remember how old he was, maybe six. He was already holding the racket very well and when he hit the ball he hit it well," she said.
Homar said she had suffered in the second set of Monday's final, which Nadal lost to Serb Djokovic before completing a 6-2 3-6 6-4 6-1 triumph.
Her musician husband had preferred not to watch the match due to nerves, she added.
"I liked the first set a lot but the second not so much because when I see that he is losing, I don't like it. I was really suffering and a lot of the time when that happens I have to turn it off,” she said.
"You get really nervous and then it is really difficult to get to sleep," she added.
Nadal is next in action in Spain's Davis Cup World Group playoff tie at home to Ukraine starting on Friday.
Homar said the world number two, who beat top-ranked Novak Djokovic to win his second US Open title on Monday, "always liked anything that was round".