Serena Williams announces pregnancy at Met Gala red carpet

Tennis star Serena Williams confirmed she is expecting baby number two on Monday, telling reporters at the star-studded Met Gala in New York that there were "three of us" on the red carpet, where she arrived with husband Alexis Ohanian.

The 23-times major winner announced last year that she was "evolving away from tennis," writing in a Vogue magazine article that she wanted to grow her family after welcoming daughter Olympia in 2017.

Williams, a long-time friend of Anna Wintour, the Vogue editor-in-chief and Met Gala co-chair, is a frequent attendee of the annual event to benefit the Metropolitan Museum of Art's Costume Institute and on Monday donned a form-fitting black gown with a white skirt.

The theme of this year's gala was "Karl Lagerfeld: A Line of Beauty," in honour of the late Chanel designer.

Footage from the red carpet showed Ohanian, an entrepreneur and the co-founder of Reddit, gently resting his hand on the midsection of the 41-year-old Williams.