As she prepares to make her return to the U.S. Open, all eyes are on six-times winner Serena Williams

But the 36-year-old was once just a little girl dreaming of stepping onto that court – as she remembers in a new advert for her sponsors Nike.

As the new mother – she welcomed baby Olympia just under a year ago – prepares for her comeback, she shared vintage family footage of herself as a small girl.

Dream big: Serena Williams is seen as a small child dreaming of the U.S. Open in heart-warming family footage as she preps for her return to the court

‘If you don’t dare to try and chase your dreams, you’ll rob yourself the joy of doing it,’ she wrote on Instagram. ‘Don’t just dream it. #JustDoIt.’

The advert opens with a pre-teen Serena on the court with her father and first coach, Richard Williams, who began training her for tennis stardom when she was just three.

Her father tells the young Serena to imagine: ‘This is you at the U.S. Open, this is you.’

Her best life: Serena posted this picture with the caption ‘It’s only a crazy dream until you do it’

Just Do It: As the new mother – she welcomed baby Olympia just under a year ago – prepares for her comeback, she shared vintage family footage of herself as a small girl

The footage then cuts between Serena the focused child, and shots of her as an adult during her six U.S. Open wins.

As Richard Williams tells the young Serena: ‘Keep that perfect service motion you have, like that,’ ‘Switch to the back hand,’ and ‘Make the net,’ we seen the adult Serena following his advice on the Open court.

The accomplished athlete currently holds the record for the most Single Gran Slams at 24. She has also won an additional 14 Grand Slam doubles titles with her older sister Venus.

Throwback: The footage cuts between Serena the focused child, and shots of her as an adult during her six U.S. Open wins

Her father tells the young Serena to imagine: ‘This is you at the U.S. Open, this is you’

‘If you don’t dare to try and chase your dreams, you’ll rob yourself the joy of doing it,’ she wrote on Instagram. ‘Don’t just dream it. #JustDoIt.’

Serena is scheduled to play her first 2018 U.S. Open match on Monday at Flushing Meadows in New York

The 36-year-old will face Magda Linette in Arthur Ashe Stadium to start the night session.

Serena has said she is ready for the Open, although she has found it tough juggling work and motherhood. On Friday, Serena had to cancel a Media Day appearance because Olympia was feeling sick.

But she returned back to work on Saturday for Arthur Ashe Kids’ Day.

As Richard Williams tells the young Serena: ‘Keep that perfect service motion you have, like that,’ ‘Switch to the back hand,’ and ‘Make the net,’ we seen the adult Serena following his advice on the Open court

Devoted: Serena was homeschooled by her dad, who began her tennis coaching when she was just three years old

Serena missed the Grand Slam event last year because she was pregnant with Olympia. During Saturday’s press conference for the U.S. Open, she found it ‘interesting’ that she’s considered a front-runner to win less than a year after giving birth.

‘You know, I don’t know my draw, but I feel like I’m going to have to play. If I want to be the best, I’m going to have to start beating these people, anyway.’

She added, ‘If anything, I can just continue to strive. That’s the message I’ve been preaching to women and people – that we face obstacles. You have to face those obstacles. Whether you get through them or not, there’s always another chance to get through them. You have to continue to work hard and believe in yourself. Things don’t always go your way, but continue to climb that mountain.’

Serena shares her little girl with her Reddit co-founder husband Alexis Ohanian, 35.

The couple tied the knot on November 16, 2017, in New Orleans, 11 weeks after their daughter was born in West Palm Beach, Florida.

Worth it: Today Serena is unmatched, holding the record for the most Grand Slam Singles wins in history

Two loves: Serena shares her little girl with her Reddit co-founder husband Alexis Ohanian, 35, seen here Monday