Venus 'super excited' to be an auntie for Serena

QUEENS, NEW YORK, USA - Venus Williams expressed her delight at becoming an aunt after sister Serena Williams reportedly became a mom for the first time.

"Obviously I'm super excited," Venus told ESPN's Pam Shriver after her third-round win over Maria Sakkari at the US Open on Friday. "Words can't describe."

Former WTA World No.1 Serena Williams is engaged to Reddit co-founder Alexis Ohanian and is widely understood to have given birth to her first child in West Palm Beach, Florida.

Williams, 35, won her seventh Australian Open title - breaking Stefanie Graf's Open Era record for her 23rd Grand Slam title - back in January, learning she was two months pregnant a day before the tournament began.

The American, who became enagaged to Ohanian at the end of December, has not played since, announcing her pregnancy to the public in April with full intent to return to tennis as early as 2018.

Tennis stars such as men's world number one Rafael Nadal paid tribute to Serena on Twitter:

WTA legend Chris Evert said: "I'm so thrilled for her. And what a role model she's going to be for her daughter."

Wimbledon champion Garbiñe Muguruza, who is also in action at Flushing Meadows, joked: “Baby girl? Well, I hope she doesn’t play tennis!"