'Don't dream it, just do it' - Serena Williams shares flashback in new ad

A new Nike ad featuring Serena Williams gives fans a glimpse into the tennis superstar's upbringing, showing vision of the 23-time Grand Slam champion learning the game.

Mentored by her father, Richard, Williams can be seen being taught how to serve, over-layed with shots of her victories at the US Open.

"It's only crazy until you do it" reads across the screen.

Taking to Twitter, Williams posted:

"If you don’t dare to try and chase your dreams, you'll rob yourself the joy of doing it. Don't just dream it. #JustDoIt"

Williams will be hoping to add a 24th major title, as the US Open begins this week.