Playing at the French Open in Paris, Venus told a TV interviewer: "She's going to call me her favorite aunt."

"We're all like, 'baby V, baby Lyn, baby Isha'. We all want the baby to be named after us," Williams told Eurosport, referring to the names of Serena's sisters.

Serena, who revealed she was pregnant in April, has refused to discuss the sex of the baby she is expecting with fiance Alex Ohanian, the founder of Reddit.

Serena is a three-time champion at Roland Garros. She was courtside on Wednesday, watching her older sister defeat Kurumi Nara in the second round.

"I think it's not easy for her to watch, because obviously she knows she can do well here," said Venus, who turns 37 next month.

"I think she's just excited about everything coming up in her life, on and off the court, excited about hopefully returning here next year."

Serena, who won her 23rd Grand Slam title in January when she defeated Venus in the Australian Open final, is due to give birth in September, the month she turns 36.

Earlier this week in Paris, Venus talked about her anticipation of becoming an aunt.

"I'm definitely looking forward to it. I have no idea what the experience will be like," she said.

"Previously I became an aunt when I was very young and lived far away, on the other side of the United States, so it was a completely different experience than it will be this time.

"So I hope that I can live up to this job. I've got to get some confidence that I can do this. It's all new for me. It's a great journey."

Serena learned she was pregnant just two days before entering the Australian Open in Melbourne.

She has told of being nervous about playing, uncertain whether it would be too dangerous for her or the baby.

Agence France - Presse